Network Pro

Client/serverExplanationIn a client/server network, hosts have specific roles. For example, some hosts are assigned server roles which allows them to provide network resources to other hosts. Other hosts are assigned client roles which allows them to consume network resources.

In a peer-to-peer network, each host can provide network resources to other hosts or accessresources located on other hosts, and each host is in charge of controlling access to thoseresources.An intranet is a private network that uses Internet technologies. Services on an intranet are only available to hosts that are connected to the private network. An extranet is a private network that uses Internet technologies, but whose resources are made available to external (but trusted) users. For example, you might create a Web site on a private network that only users from a partner company can access.

Peer-to-peerExplanationIn a peer-to-peer network, each host can provide network resources to other hosts or access resources located on other hosts, and each host is in charge of controlling access to those resources.In a client/server network, hosts have specific roles. For example, some hosts are assigned server roles which allows them to provide network resources to other hosts.

Other hosts are assigned client roles which allows them to consume network resources.Polling is a media access method where a single device grants permission to other devices to access the network. Multiple access describes a media access method where each device determines when the medium is free.

Messages are broadcast to all devices connected to the network.ExplanationMessages sent using a physical bus topology are broadcast to all devices in the network. The device in the middle of the star (typically a hub), receives the message and forwards it on to all other devices.

RingExplanationIn ring topologies, each device on the network acts as a repeater to send the signal to the next device.

RingExplanationIn ring topologies, each device is connected to a neighboring device, until a ring is formed.

Messages travel from one device to the next until they reached the destination device.ExplanationIn a logical ring topology, messages travel to each device in turn. If the message is not intended for that device, the message is forwarded to the next device on the network.

StarExplanationA hub creates a network with a physical star topology. The physical star topology uses a logical bus topology, where messages are sent to all devices connected to the hub. A mesh topology is a series of point-to-point links between devices. A ring topology uses a central device called an MSAU.

MeshExplanationIn a mesh topology, each network device is interconnected to all other network nodes. This creates multiple data paths and in the event of a failed link, the data has an alternate route to arrive at its destination.The star topology connects network devices to the network with a single patch cable and the failure of a patch cable will make the connected device unavailable.

The bus topology has a single point of failure, if there is a break in the network media, the network will be unavailable. A single break in a physical ring topology will disable the network.

MeshExplanationThis type of network uses a physical mesh topology. The key characteristics of a mesh topologyare: • There's no central connecting point.

• Any host can communicate directly with any other host on the network. A mesh network, such as this one, is usually impractical on a wired network. Each host would have to have a separate, dedicated network interface and cable for each host on the network. However, a mesh topology can be implemented with relative ease on a wireless network due to the lack of wires.

MeshExplanationA mesh topology has multiple connections at each node, increasing connectivity fault tolerance. None of the other topologies have native fault tolerance built in.

BusExplanationThe bus topology connects all devices to a trunk cable.

SwitchExplanationA physical star topology uses a switch or a hub. Routers are used to connect multiple subnets together. A firewall is a router that performs filtering on packets or other information contained in network communications.

StarExplanationStar topologies connect each device on the network to a central hub.

IMAP4 & POP3ExplanationIMAP4 allows a mail server to hold messages for a client. POP3 is a simpler protocol than IMAP4 that downloads email messages and deletes them from the server by default, but most newer POP3 clients provide an option to leave mail on the server after download. SMTP allowsa user to send email to a server. The NTP protocol synchronizes the clocks of all computers on a network.

HTTPExplanationHTTP or HyperText Transfer Protocol is used by Web servers and browsers to transmit Web pages on the Internet. This is often confused with HTML or HyperText Markup Language which is the markup language used to create Web content.

FTP & TFTPExplanationUNIX computers use TCP/IP, as do Windows 2000 computers. Therefore, the TCP/IP utilities FTP and TFTP will both allow you to transfer files.

POP3ExplanationThe POP3 protocol is part of the TCP/IP protocol suite and used to retrieve email from a remote server to a local client over a TCP/IP connection. SNMP is a protocol used to monitor network traffic. SMTP is a TCP/IP protocol used to send email. FTP is used to transfer files.

FTPExplanationYou should implement the File Transfer Protocol (FTP). It enables file transfers and supports user authentication. The Trivial File Transfer Protocol (TFTP) enables file transfer, but does not support user authentication.

ICMPExplanationThe Internet Control Message Protocol (ICMP) allows hosts to exchange messages to indicate the status of a packet as it travels through the network.

SMTPExplanationThe Simple Mail Transfer Protocol (SMTP) specifies how messages are exchanged between email servers. POP3 and IMAP4 are used by email clients to download email messages from email servers.

FTP is a file transfer protocol. ICMP is used in ping and traceroute for communicating network communication information.

NTPExplanationThe network time protocol (NTP) lets you keep clocks synchronized.

SMTPExplanationSMTP sends email to a mail server.

IMAPExplanationThe Internet Message Access Protocol (IMAP) is an email retrieval protocol designed to enable users to access their email from various locations without the need to transfer messages or files back and forth between computers.

Messages remain on the remote mail server and are not automatically downloaded to a client system. POP3 is an email retrieval protocol that downloads and then deletes messages from a mail server. POP3 is well suited for reading email offline? however, you need to go online when you want to receive and send new messages. Once your new messages have been downloaded to your computer you can log off to read them.

This option is often used when email is received over a dialup connection.

TransportExplanationThe Transport layer is responsible for connection services that provide reliable message delivery through error detection and correction mechanisms. Specifically, the TCP protocol provides these services. The Application layer integrates network functionality into the host operating system, and enables network services. The Session layer's primary function is managing the sessions in which data is transferred.

The Data Link layer defines the rules and procedures for hosts as they access the Physical layer.

TCPExplanationWrite the application to use the Transmission Control Protocol (TCP). TCP guarantees delivery through error checking and acknowledgments.

Reliable message delivery, Data segmentation and reassembly, & End-to-end flow controlExplanationThe Transport layer is responsible for taking upperlayer data, breaking it into segments, and providing for reliable communications through end-to-end flow control and error correction and detection. Transmitting messages through the media is performed at the Physical layer. Media access, logical topology, and device identification occurs at the Data Link layer. Path identification and selection is a function of the Network layer. Data formatting is performed at the Presentation layer.

Routes messages between networksExplanationThe Network layer is responsible for routing messages between networks.

Movement of data across network cablesExplanationThe Physical layer is concerned with how to transmit data and how to connect network hosts.

Enabling communication between network clients and servicesIntegration of network functionality into the host operating systemExplanationThe Application layer enables network services, and integrates network functionality into thehost operating system. Applications actually run above the OSI Application layer.Conversation identification is accomplished at the Session layer through connection ortransaction ID numbers.

Data translation is performed at the Presentation layer.

Controlling how messages are propagated through the network.Identifying physical network devices.ExplanationThe Data Link layer controls identifying devices on a network as well as how messages travel through the network (the logical topology).The other functions listed here are performed by the Physical layer.

Connection establishmentExplanationConnection establishment is controlled through Session layer protocols.

Coordinates rules for transmitting bits.ExplanationThe OSI Physical layer coordinates rules for transmitting bits.

Defining a unique hardware address for each device on the networkLetting devices on the network have access to the LANExplanationThe MAC sublayer defines a unique MAC or datalink address for each device on the network. This address is usually assigned by the manufacturer. The MAC sublayer also provides devices with access to the network media.

ExplanationThe Data Link layer is split into the following sublayers: • Logical Link Control (LLC) Sublayer Provides the operating system link to the device driver.• Media Access Control (MAC) Sublayer Translates generic network requests into device specific terms.

Encrypt and compress dataSpecify data format (such as file formats)ExplanationThe Presentation layer encrypts data, changes and converts character sets, and compresses data.

File formats (such as .jpg, .wmv, and .wav) are part of the Presentation layer. The Application layer provides network services. The Session layer maintains separate clientconnections through session IDs, and maintains those sessions.

Flow control and error detection are provided at both the Transport layer and the Data Link layer. Transmitting frames happens at the Physical layer.

TCPExplanationThe TCP protocol includes error checking.

Low overheadConnectionless datagram servicesExplanationUDP is a connectionless protocol used by applications that need low overhead and do notrequire guaranteed delivery.

PlenumExplanationPlenum cable is fire resistant and nontoxic? it must be used when wiring above ceiling tiles.

PVC cable cannot be used to wire above ceilings because it is toxic when burned. Cat 5e cables provide better EMI protection than Cat 5 cables, and Cat 6e cables are an improvement over Cat 6 specifications, but neither are a requirement for using in a ceiling area. If the area has a lot of EMI, you might consider using STP or fiber optic cables, but this would not be a requirement just because wires were in a ceiling area. Typically, you can avoid EMI sources by rerouting cables.

You want to connect your computer to the Internet with a dialup connection.ExplanationRJ11 connectors are typically used for telephones and modems.

No, Category 5 cabling has more twists per inch than Category 3 cabling to reduce crosstalk and support higher data rates.ExplanationWhile Category 3 and Category 5 cabling may appear similar physically, they are electricallydifferent. Category 5 cabling is twisted much tighter than Category 3 cabling. This reduces

When connecting a phone to a phone line.ExplanationAn RJ11 connector is used for connecting analog telephones to the telephone jacks. Cat 3, Cat 5, and higher twisted pair cables use RJ45 connectors.

Coaxial cables use Ftype or BNC connectors. Fiber optic cables use a variety of connectors (RC, RT, LC, MTRJ).

Streaming videoExplanationCategory 6 cable is specified to extend the available bandwidth from 100 MHz to 200 MHz. This serves as the basis for greater capacity, throughput and reliability. Producing high quality streaming multimedia usually requires consistent highspeed network bandwidth.Email and messaging are typically low bandwidth applications consisting of small, brief transmissions.

Printing typically consists of greater amounts of data being transferred, however printing is highly amenable to delays and buffering and usually will not suffer any noticeableeffects with decreased bandwidth.

Cat 6ExplanationCat 6 cables include a solid plastic core that keeps the twisted pairs separated and prevents the cable from being bent too tightly.

F-typeExplanationUse an F-type connector for broadband cable connections that use coaxial cable. Use a BNC connector for 10Base2 Ethernet networks. Use an RJ11 connector for modem connections to a phone line.

Use an RJ45 connector for an Ethernet network that uses twisted pair cable. Use ST and SC connectors for fiberoptic cables.

RG59ExplanationRG6 has an impedance rating of 75 ohms. When using coaxial cables, it is important to use cables with the same impedance rating. Only RG59 is rated for 75 ohms. RG8 and RG58 are rated for 50 ohms.

RG6 & RG59ExplanationF-type connectors are used with coaxial cable, and are typically used for cable TV and satellite installations using RG6 or RG59 cables.

RG58 cables typically use BNC connectors and cables are used for 10Base2 Ethernet. Cat 5, 5e, and 6e cables use RJ45 connectors.

RG6 & RG59ExplanationBoth RG6 and RG59can be used for cable and satellite networking applications, although RG6 has less signal loss than RG59, and is a better choice for networking applications, especially where longer distances (over a few feet) are involved. Both RG6 and RG59 have an impedance rating of 75 ohms.

RG8 and RG58 have an impedance rating of 50 ohms and were used with 10 Mbps Ethernet.

RG6ExplanationCoaxial cable offers better protection against EMI than twisted pair cables. Coaxial cable has a mesh conductor which provides a ground and protects against EMI. In general, the higher the twisted pair cable standard, the better protection against some forms of EMI (typically crosstalk). For twisted pair, use shielded twisted pair instead of unshielded twisted pair. Use fiber optic for the best protection against EMI.

It has a conductor made from copper in the center of the cable.It uses two concentric metallic conductors.The ends of the cable must be terminated.ExplanationCoaxial cable is composed of a central copper conductor surrounded by an insulator which is then surrounded by a second metallic mesh conductor.

The name coaxial is derived from the fact that both of these conductors share a common axis. When using coaxial cable, both ends of the cable must be terminated.

They use a housing and latch system similar to an RJ45 UTP connector.

They are half the size of standard connectors.ExplanationLC fiber optic connectors are small? about half the size of other fiber optic connectors. Their appearance is similar to a typical RJ45 connector used with UTP wiring. Like an RJ45 connector, it uses a small latch to lock the connector in a jack.

Single mode fiber opticExplanation Fiber optic cables offer the best protection against electromagnetic interference (EMI).

Single modeExplanationIn this scenario, use single mode fiber optic cables.

Fiber optic is graded as single mode or multimode. Single mode consists of a single very thin core which produces fewer reflections. This provides greater effective bandwidth over greater distances. Multimode is less costly than single mode fiber. Multimode transmits multiple light rays concurrently. Multimode is used to transmit over shorter distances as the rays tend to disperse as the transmission distance increases.

Fibre channel is a network topology used in storage area networks.

They can be used with multimode fiber optic cables.They use metal guide pins to ensure accurate alignment.

ExplanationMTRJ connectors can be used with either multimode or single-mode fiber optic cabling. The connector is made from plastic and uses metal guide pins to ensure it is properly aligned in the jack.

The central core is smaller than that of multimode fiber optic cabling.ExplanationSingle mode fiber optic cabling transmits a single ray (or mode) of light through glass or plastic fiber.

It supports longer transmission distances than multimode fiber optic cable and is also more expensive. It also has a central core that is much smaller than that of multimode fiberoptic cabling.

Immunity to electromagnetic interferenceGreater cable distances without a repeaterExplanationCompared to other types of cabling, fiber optic cabling allows greater cable distances without arepeater and is immune to electromagnetic interference.

However, installation costs more andtakes longer.

STExplanationThe ST connector is used with fiber optic cable and uses a twist-type connector. Tip: To remember the difference between ST and SC connectors, associate the T in ST with "twist". SC and LC connectors are used with fiber optic cables but plug in instead of twist. F-typeand BNC connectors use a twist to connect, but are used with coaxial cables.

MTRJLCExplanationBoth the LC and MTRJ connectors have both fiber optic cables in a single connector. ST and SC connectors hold a single strand of fiber optic cable. A cable using either connector has two connectors on each end.

A BNC connector is used with coaxial cable.

SC & STExplanationThe fiber optic cable assembly process is more complex than other assemblies. It is necessary to polish the exposed fiber tip to ensure that light is passed on from one cable to the next with no dispersion.

MDFExplanationThe main distribution frame (MDF) is the main wiring point for a building. The MDF is typically located on the bottom floor or basement.

The LEC typically installs the demarc to the MDF. An intermediate distribution frame (IDF) is a smaller wiring distribution point within a building. IDFs are typically located on each floor directly above the MDF, although additional IDFs can be added on each floor as necessary.A horizontal cross connect connects wiring closets on the same floor. A smart jack is a special loopback plug installed at the demarcation point for a WAN service.

Technicians at the central office can send diagnostic commands to the smart plug to test connectivity between the central office and the demarc. Use 66 and 110 blocks to connect individual wires within a wiring closet.

Use the T568A standard on one connector, and the T568B standard on the other connector.ExplanationThe easiest way to create a crossover cable is to arrange the wires in the first connector using the T568A standard and arrange the wires in the second connector using the T568B standard. A crossover cable connects the transmit pins on one connector to the receive pins on the otherconnector (pin 1 to pin 3 and pin 2 to pin 6).

Keep wire pairs twisted up to within one-half of an inch of the connector.ExplanationWhen using for Cat5 (or higher) wiring, be sure to preserve the twists in each wire pair to within one-half of an inch of the connecting block.Use C4 connectors to connect four pairs of wires. When connecting data wires on a 110 block, you typically connect wires in the following order:• White wire with a blue stripe, followed by the solid blue wire.

• White wire with an orange stripe, followed by the solid orange wire.• White wire with a green stripe, followed by the solid green wire.• White wire with a brown stripe, followed by the solid brown wire.T568A and T568B are used to connect wires within an RJ45 connector when making drop cables.

Crimping toolExplanationYou should use a crimping tool designed for RJ45 connectors to attach connectors to UTP cable.

IDFExplanationAn intermediate distribution frame (IDF) is a smaller wiring distribution point within a building. IDFs are typically located on each floor directly above the MDF, although additional IDFs can be added on each floor as necessary. The main distribution frame (MDF) is the main wiring point for a building. The MDF is typically located on the bottom floor or basement.

The LEC typically installs the demarc to the MDF. A vertical cross connect connects the MDF on the main floor to IDFs on upper floors. Cabling runs vertically (up and down) between the MDF and the IDFs. A horizontal cross connect connects IDFs on the same floor.

Cabling runs horizontally (sideways) between the IDFs. A demarc extension extends the demarcation point from its original location to another location within the building.

Punchdown toolExplanationA demarc is the location where the local network ends and the telephone company's network begins. This location is usually at a punch down block in a wiring closet. You use a punchdown tool to attach wires to the punch down block.

DemarcExplanationWhen you contract with a local exchange carrier (LEC) for data or telephone services, they install a physical cable and a termination jack onto your premises.

The demarcation point (demarc) is the line that marks the boundary between the telco equipment and the privatenetwork or telephone system. Typically, the LEC is responsible for all equipment on one side of the demarc, and the customer is responsible for all equipment on the other side of the demarc. A smart jack is a special loopback plug installed at the demarcation point for a WAN service.Technicians at the central office can send diagnostic commands to the smart plug to test connectivity between the central office and the demarc. A punchdown block is a block used to connect individual copper wires together. While the demarc might terminate in a punchdownblock, punchdown blocks are used within other locations at the customer site.

An intermediate distribution frame (IDF) is a smaller wiring distribution point within a building. IDFs are typically located on each floor directly above the main distribution frame (MDF), although additional IDFs can be added on each floor as necessary. A vertical cross connect connects the IDF to the MDF on a different floor.

Use a punchdown tool with a notched blade.Point the cut side of the tool towards the wire end.

Explanation Use a punchdown tool to connect wires to a 110 or 66 block. When using a punchdown tool, choose the right blade for the job:• Use a notched blade for a 110 block. • Use a straight blade for a 66 block.• For both blade types, you can use the end without a cutting blade if you want to punch down without cutting the wire. When using the cutting blade, point the cut side of the punchdown tool towards the wire end that you want to trim.

Cable stripperExplanationUse a cable stripper to remove the plastic covering for a cable. Note: When making drop cables or using punchdown blocks, do not remove the plastic covering for individual wires.

Use snips to cut cables. Use a punchdown tool to push wires into 66 or 110 blocks and cut wires at the same time. Use a butt set to connect to phone lines to monitor, make, or answer phone calls.

Demarc extensionExplanationA demarc extension extends the demarcation point from its original location to another location within the building.

The demarc extension typically consists of a single wire bundle that attaches to the existing demarc and supplies a termination point to a different location. Youmight need a demarc extension if your network occupies an upper floor of a building. The LEC will typically install the demarc into the MDF on the bottom floor, and you will need to install an extension to place the demarc into the IDF on your floor. A horizontal cross connect connects IDFs on the same floor.

Cabling runs horizontally (sideways) between the IDFs. A smart jack is a special loopback plug installed at the demarcation point for a WAN service. Technicians at the central office can send diagnostic commands to the smart plug to test connectivity between the central office and the demarc. Use 66 and 110 blocks to connect individual wires within a wiring closet. These blocks can be used to connect devices to the WAN service wiring, but are not typically used for installing a demarc extension.

Vertical cross connectExplanationA vertical cross connect connects the main distribution frame (MDF) on the main floor to intermediate distribution frames (IDFs) on upper floors. Cabling runs vertically (up and down) between the MDF and the IDFs. A horizontal cross connect connects IDFs on the same floor. Cabling runs horizontally (sideways) between the IDFs.

A smart jack is a special loopback plug installed at the demarcation point for a WAN service. Technicians at the central office can send diagnostic commands to the smart plug to test connectivity between the central office and the demarc. A demarc extension extends the demarcation point from its original location to another location within the building. The demarc extension typically consists of a single wire bundle that attaches to the existing demarc and supplies a termination point to a different location.

You might need a demarc extension if your network occupies an upper floor of a building. The LEC will typically install the demarc into the MDF on the bottom floor, and you will need to install an extension to place the demarc into the IDF on your floor.

Pin 1 & Pin 2ExplanationOn a 100BaseT network cable, the RJ45 pinouts are as follows:• Pin 1: Tx+• Pin 2: Tx-•Pin 3: Rx+• Pin 4: Unused• Pin 5: Unused• Pin 6: Rx-•Pin 7: Unused• Pin 8: Unused

White/green, green, white/orange, blue, white/blue, orange, white/brown, brownExplanationThe T568A standard uses the following order of wires in the connector: White/green, green, white/orange, blue, white/blue, orange, white/brown, brown.

The T568B standard switches the orange and green wires (along with their corresponding white wires). Use the order Blue-Orange-Green-Brown (BLOG), with the white wire first, for connecting wires on a 110 punchdown block.

110 blockExplanationA 110 block is a punchdown block that uses metal clips fitted over plastic pins. When connecting wires using a 110 block, place the wires in the plastic slots, attach the metal clip, then punch down the connecting cable on the top of the clip. A 66 block uses metal pins for connecting wires.

Wires are placed in the pins, and pins within a row are electrically connected. 25 pair and 100 pair are cable bundles that include multiple pairs of copper wires (either 25 pairs of wires or 100 pairs of wires).

White/blue, blue, white/orange, orange, white/green, green, white/brown, brownExplanationWhen connecting data wires on a 110 block, you typically connect wires in the following order:• White wire with a blue stripe, followed by the solid blue wire.• White wire with an orange stripe, followed by the solid orange wire.• White wire with a green stripe, followed by the solid green wire.

• White wire with a brown stripe, followed by the solid brown wire.Tip: Use BLOG (blue-orange-green) to remember the wire order, and remember to start with the white striped wire first.When adding RJ45 connectors to a drop cable, use one of the following orders, based on the standard you want to follow:• T568A- To use this standard, arrange the wires from pins 1 to 8 in each connector in the following order: GW, G, OW, B, BW, O, BrW, Br.• T568B- To use this standard, arrange the wires from pins 1 to 8 in each connector in the following order: OW, O, GW, B, BW, G, BrW, Br.

Punchdown toolExplanationUse a punchdown tool to push wires into 66 or 110 blocks and cut wires at the same time. The punchdown tool has a blade on one side the cuts off the excess wires. Use snips to cut cables or wires. However, a punchdown tool would be easier to use for this task than wire snips.

Use a cable stripper to remove the plastic covering for a cable. Note: When making drop cables or using punchdown blocks, do not remove the plastic covering for individual wires. Use a butt set to connect to phone lines to monitor, make, or answer phone calls.

Patch panelExplanationA patch panel is a device that typically connects individual stranded wires into female RJ45 connectors. For example, you might connect 4 pairs of wires from a punchdown block to a port on the patch panel.

On the patch panel, you then connect drop cables (cables with RJ45connectors) to the patch panel on one end and a computer on the other end. Use 66 and 110 blocks to connect individual wires within a wiring closet. These punchdown blocks connect the individual wires together, but do not terminate in RJ45 connectors. A horizontal cross connect connects IDFs on the same floor.

White/orange, orange, white/green, blue, white/blue, green, white/brown, brownExplanationThe T568B standard uses the following order of wires in the connector: White/orange, orange, white/green, blue, white/blue, green, white/brown, brown.

The T568A standard switches the green and orange wires (along with their corresponding white wires). Use the order Blue-Orange-Green-Brown(BLOG), with the white wire first, for connecting wires on a 110 punchdown block.

25 pairHorizontal cross connectExplanationA horizontal cross connect connects wiring closets on the same floor. 25 pair or 100 pair wiring punched down into 66 or 110 blocks are often used to connect the wiring closets together. A vertical cross connect connects the IDF to the MDF on a different floor.

The demarcation point (demarc) is the line that marks the boundary between the telco equipment and the private network or telephone system. A demarc extension extends the demarcation point from its original location to another location within the building. A smart jack is a special loopback plug installed at the demarcation point for a WAN service. Technicians at the central office can send diagnostic commands to the smart plug to test connectivity between the central office and the demarc.

ARPExplanationHosts use the Address Resolution Protocol (ARP) to discover the hardware address of a host.

AB.07.CF.

62.16.BDExplanationMAC addresses are comprised of 12 hexadecimal digits (ranging from 09 and AF). They are typically represented as a three sets of four hexadecimal digits or six sets of two hexadecimal digits separated with periods. Regardless of the grouping and separator values, look for 12 hex digits for a valid MAC address.

TransceiverExplanationA transceiver (short for transmitter/receiver) sends signals to and receives signals from the network. It translates the parallel data stream of the computer to the serial data stream of the network and vice versa. Most transceivers are now built into network interface cards (NICs).

It is a 48-bit address.It is typically represented by hexadecimal numbers.ExplanationThe MAC address identifies the physical address of the network adapter. The MAC address is a 12-digit (48-bit) hexadecimal number (each number ranges from 09 or AF).

The address is often written as 00B0D006BCAC or 00B0.D006.BCAC, although dashes, periods, andcolons can be used to divide the MAC address parts. An IPv4 address is 32bits and uses octets of decimal numbers between 0255. An IPv6 address is a 64-bit address that uses 32 hexadecimal numbers.

Network interface cardExplanationThe network interface card (NIC) allows a device to send and receive messages over the transmission media.

C0-34-FF-15-01-8EExplanationA MAC or hardware address is a unique identifier hard coded on every network adapter card. A valid MAC address has a total of 12 hexadecimal numbers. Hexadecimal numbers contain the numbers 0 to 9 and the letters A to F. Valid values in a MAC address range anywhere from 00 to FF. Note that one of the answers would be a valid MAC address except it uses a G value, which is beyond the range of a hexadecimal number.

Layer 1ExplanationA media converter operates at the OSI model layer 1 (Physical layer). The media converter translates frames into bits and transmits them on the transmission medium. At layer 2, the MAC address is added to make the data into a frame. At layer 3, the IP address is added to the packet. A media converter does not alter or use the MAC address or the IP address.

Media converterExplanationUse a media converter to convert from one media type to another media type within the same architecture. Use a bridge to connect two devices that use different network architectures, for example to connect a wired network to wireless clients. A hub or a repeater connect devices using the same media type.

GBIC & SFPExplanationOlder network adapters used an external transceiver that matched the media type. While nearly all current network adapters come with a built in transceiver type, new devices, such as switches and routers, use transceiver modules that allow you to modify the media type of aport by changing the transceiver. Transceiver modules include the following:• A GBIC (gigabit interface converter) is a larger sized transceiver that fits in a port slot and is used for Gigabit media including copper and fiber optic.• An SFP (small formfactor pluggable) is similar to a GBIC but with a smaller size. An SFP is sometimes called a miniGBIC.• An XFP transceiver is similar in size to an SFP but is used for 10 Gigabit networking.

It modulates digital data from the PC into analog data and transmits it on a telephone network.It demodulates analog data from a telephone network into digital PC data.ExplanationModem is shorthand for modulator/demodulator. Its job is to convert (or modulate) digital data from a PC into analog telephone signals and transmit them through a telephone network. It also receives analog data from the telephone network and converts (or demodulates) it intodigital PC data.

Bridges, Switches & NICsExplanation Network interface cards (NICs), bridges, and switches all operate at the OSI Data Link layer. They use the physical device address (MAC address) to identify packets. Hubs and repeaters operate at the Physical layer they simply repeat packets without regard to addresses. Routersfunction at the Network layer they examine the logical device and network address to perform routing tasks.

Hub & RepeaterExplanationA hub and a repeater send received signals out all other ports. These devices do not examine the frame or the packet contents. A switch or a bridge use the MAC address in a frame for forwarding decisions. A router uses the IP address in a packet for forwarding decisions.

It connects multiple cable segments (or devices), and forwards frames to the appropriate segment.ExplanationSwitches have multiple ports and can connect multiple segments or devices. The switch forwards frames to the appropriate port. They function similarly to a hub, except instead of sending packets to all ports, switches send packets only to the destination computer's port.

Data LinkExplanationSwitches are associated with the Data Link layer of the OSI model. Switches examine the device address in the packet and forward messages directly to that device.

When a frame enters a port, the source MAC address is copied from the frame header.ExplanationBridges and switches learn addresses by copying the MAC address of the source device and placing it into the MAC address table. The port number which the frame entered is also recorded in the table and associated with the source MAC address. The switch or the bridge cannot record the destination MAC address because it does not know the port that is used to reach the destination device. Bridges and switches operate at Layer 2 and do not use IP addresses (which exist at Layer 3).

HubExplanationAn access point functions like a hub by connecting multiple wireless hosts to a wired Ethernet network.

PhysicalExplanationHubs operate at layer 1, or the Physical layer of the OSI model.

Data LinkExplanationThe bridge is operating at the Data Link layer.

Switch & Network interface cardExplanationA network interface card and a switch operate at layer 2 (Data Link) of the OSI model. Layer 2 includes protocols that define the MAC address. The MAC address is burned into the network interface card, and a switch uses the MAC address to make forwarding decisions. A hub or a repeater operate at layer 1? they regenerate a signal without looking at layer 2 or layer 3 information. A router operates at layer 3, using the IP address to make forwarding decisions. A firewall operates at layer 3 or higher, using packet or data contents for makingfiltering decisions.

Send the frame out ports 2-8.ExplanationBecause the switch does not know the port that is used to reach the destination device, it will send the frame out all ports except for the port on which the frame was received. After the switch learns the port that is used to reach the destination device, it will send the frame outonly that port.

SwitchExplanationA switch offers guaranteed bandwidth to each port.

FirewallExplanationA firewall is the best device to deploy to protect your private network from a public untrusted network. Firewalls are used to control traffic entering and leaving your trusted network environment. Firewalls can manage traffic based on source or destination IP address, portnumber, service protocol, application or service type, user account, and even traffic content. Routers offer some packet based access control, but not as extensive as that of a full-fledged firewall. Hubs and gateways are not sufficient for managing the interface between a trusted and an untrusted network.

FirewallExplanationThe role of a firewall is to provide a barrier between an organization's network and a public network, such as the Internet. Its job is to prevent unauthorized access into the organization's private network. To do this, the firewall examines incoming packets and determines whetherthey should be allowed to enter based on a set of rules defined by the network administrator.

NetworkExplanationA router uses the logical network address specified at the Network layer to forward messages to the appropriate LAN segment. A bridge, on the other hand, uses the MAC address and works at the Data Link layer.

RouterExplanationA router is a device that links multiple networks and directs traffic between networks. Each network linked by routers has its own unique identifier called the "network number" or"network address."

Layer 3ExplanationA router operates at layer 3, or the Network layer.

FirewallExplanationA firewall allows you to filter unwanted traffic from the Internet to your network. Packet Internet Groper is better known by its acronym, PING, a TCP/IP command. A proxy server caches web pages. ICS allows you to connect a small network to the Internet through a singleconnection.

Maintain information about paths through an internetworkRoute data based on logical network addressesExplanationRouters build and maintain tables of routes through an internetwork, and deliver data between networks based on logical network addresses.

The device listens to determine if the transmission media is free.ExplanationThe IEEE 802.3 committee describes the CSMA/CD media access method. Devices listen to the network to determine if the transmission media is free before transmitting.

RJ45ExplanationRJ45 connectors are used with Ethernet 10-BaseT networks.

CSMA/CDExplanationCarrier sense multiple access with collision detection (CSMA/CD) is the media access control method of all Ethernet networks.

Bus & StarExplanationEthernet networks use either a physical bus or physical star topology. Hubs can also be cascaded to form a tree topology.

1000BaseT10BaseTExplanationCSMA/CD stands for Carrier Sense Multiple Access / Collision Detection. It defines the steps network devices take when two devices attempt to use a data channel simultaneously. Ethernet networks use CSMA/CD, including 10BaseT, 10Base2 and 1000BaseT.

Single mode fiber10GBaseER standards10GBaseLR standardsExplanationFor 10 Gbps Ethernet at distances of 10 kilometers or more, use singlemode fiber optic cable. 10GBaseLR (up to 10 km) and 10GBaseER (up to 40 km) both support 10 Gbps single mode fiber. Multimode fiber is cheaper but has a shorter maximum distance than single mode fiber.10GBaseSR uses multimode fiber at distances up to 300 meters.

100 metersExplanationWith an Ethernet 10BaseT network, the maximum cable length between a computer and thehub is 100 meters.

100BaseFX1000BaseLXExplanation100BaseFX and 1000BaseLX are Ethernet standards that use fiberoptic.Following the Ethernet naming conventions:• F designates fiberoptic cables. Ethernet standards with the F designation are 10BaseFL and 100BaseFX.• L designates "long" distances and requires fiberoptic to support the distance. Ethernet standards with the L designation are 10BaseFL, 1000BaseLX, and 10GBaseLR.• S designates "short" distances that use fiberoptic cables. Ethernet standards with the S designation are 1000BaseSX and 10GBaseSR.• T designates twisted pair cables. Ethernet standards with the T designation are 10BaseT, 100BaseTX, 100BaseT4, and 1000BaseT.• C designates copper cables. The 1000BaseCX standard is for fast Ethernet at short distances within wiring closets.

2000 metersExplanationThe maximum length for a 10BaseFL network segment is 2000 meters (2 km). Because a 10baseFL network uses a physical star topology, a segment is defined as one of the arms of the star, (between the hub and a host). That means the fiberoptic cable between the hub and a workstation can be up to 2000 meters long. 100BaseFX supports up to 412 meters. 1000BaseSX and 1000BaseLX support up to 550 meters. 100 meters is the maximum twisted pair cable length.

10GBaseLWExplanation10GBase standards ending in W are used for SONET implementations. These include 10GBaseSW (short), 10GBaseLW (long), and 10GBaseEW (extended). 10GBaseER is for extended fiber optic but not used with SONET. 1000Base standards are not used for SONET. 1000BaseCX is a copper cable specification.

Type 1A STP or Category 5 UTPExplanationEither Type 1A STP or category 5 UTP can be used with 100BaseTX Fast Ethernet networks.

412 metersExplanationFor 100BaseFX, halfduplex, multimode cable has a maximum segment length of 412 meters. 1000BaseSX and 1000BaseLX support multimode cable up to 550 meters. 10BaseFL supports fiber optic cable between 1,000 and 2,000 meters.

1000BaseCXExplanationThe 1000BaseCX standard specifies 150ohm STP cabling. The maximum cable length is 25 meters. The 10BaseFL, 1000BaseSX, 1000BaseLX, and 1000BaseZX standards employ fiberoptic cabling. 1000BaseT uses Category 5 UTP instead of STP cabling.

Physical star/logical busPhysical star/logical starExplanation100BaseTX Fast Ethernet networks use a physical star/logical bus topology when a hub is used or a physical star/logical star when a switch is used.

Cat 3 & Cat 4Explanation1000 Mbps Ethernet (Gigabit Ethernet) requires at least Cat 5 cables. While Cat 5 supports 1000 Mbps, it can have poor performance during high-data transfers. Whenever possible, it is best to use a higher grade cable (Cat 5e or Cat 6) if you want 1000 Mbps data transmission.Cat 3 only supports 10 Mbps Ethernet. Cat 5e or Cat 6 is required for 10 Gbps Ethernet.

Fiber opticExplanationEthernet 100BaseFX networks use fiber optic cabling.

1000BaseLXExplanation1000BaseLX supports segment lengths of up to 5 km when used with fiber-optic cable. This maximum segment length is cut to 550 m when fiber-optic cable is used and it operates in half-duplex. 1000BaseSX supports segment lengths of only 550 meters. 1000BaseCX uses copper wire and supports segment lengths of only 25 meters. 1000BaseT uses twisted pair cables.

1000BaseSXExplanationThe 1000BaseSX standard uses fiberoptic cable with a maximum segment length of 550 meters. However, to implement segments this long, you must use 50 micron, 500MHz/km fiber optic cable. Other types of cable will shorten the maximum segment length. 1000BaseFX alsosupports lengths up to 550 meters. 1000BaseFX supports distances up to 10 kilometers. 1000BaseZX has a maximum segment length of up to 100 km. 1000BaseCX and 1000BaseT use copper cabling instead of fiberoptic.

1000BaseLXSingle mode fiberExplanationOf the standards listed in this question, 1000BaseLX provides the greatest cable length (think of the "L" in 1000BaseLX as "long"). When using long distances for fiber optic, use single mode fiber. Multimode fiber is cheaper but has a shorter maximum distance than single mode fiber. 1000BaseSX is for short fiber optic, and 1000BaseCX uses short copper within a wiring closet.

1000BaseSX10GBaseSRExplanation10GBaseSR and 1000BaseSX can operate within these parameters. Both will support segment lengths 300 meters long and operate using full-duplex. 10BaseFL isn't a good choice because its data transmission rate is relatively slow. 1000BaseCX and 1000BaseT both use copper wiring.

RJ45 connectorsCAT 5 cablingThe cable length must be less than or equal to 100mExplanationGigabit Ethernet (1000BaseT) has similar requirements to 100BaseT with connectors, cabling,and distances. The network cards are simply designed to transfer data ten times as fast.

100 metersExplanationFast Ethernet using twisted pair cables (either 100BaseT4 or 100BaseTx) has a maximum cable segment length of 100 meters. Tip: All Ethernet networks that use twisted pair cable (Ethernet, Fast Ethernet, Gigabit Ethernet) have a distance limitation of 100 meters.

RolloverExplanationUse a rollover cable to connect a workstation to the console port of a router or a switch. The rollover cable has an RJ45connector on one end to connect to the console port, and a serial connector on the other end to connect to the serial port of the workstation. You then run a terminal emulation program on the workstation to connect to the console of the router or switch to perform configuration and management tasks. Use a straight-through or crossover Ethernet cable to connect devices using the Ethernet RJ45ports. An RG6 cable is a coaxial cable.

CrossoverExplanationUse a crossover cable to connect two switches through their uplink ports, or to connect the two switches through regular ports. Use a straight-through cable to connect the uplink port on one switch to a regular port on another switch. Use a rollover cable to connect a workstation to the console port of the switch. Use a loopback plug connected to a single port for troubleshooting.

CrossoverExplanationUse a crossover cable to connect a workstation or a router to the uplink port on a switch. Use a straight-through cable to connect the router to a regular switch port. Use a rollover cable to connect a workstation to the console port of a router. Use a loopback plug to allow a deviceto communicate with itself through its own network adapter.

CrossoverExplanationUse a crossover cable to connect two devices together in a back-to-back configuration. Use a straight-through cable to connect a workstation to a hub or switch port. Use a rollover cable to connect a workstation to the console port of a router or a switch. Use a loopback plug to allow a device to communicate with itself through its own network adapter.

RS-232Explanation A rollover cable has a serial connector on one end and an RJ-45 connector on the other end. RS-232 is the standard for serial communications. RJ-11 connectors are used for analog telephone lines. RG-6 and RG-58 are coaxial cable standards.

Straight-throughExplanationUse a straight-through cable to connect a workstation or router to a regular switch port. Use a crossover cable to connect the workstation to the uplink port. Use a rollover cable to connect the workstation to the console port of the switch. Use a loopback plug to allow a workstation to communicate with itself through its own network adapter.

SerialExplanationA rollover cable has a serial connector on one end and an RJ45 connector on the other end. Alternatively, it might have an RJ45 connector on both ends, and a serial converter is used to convert from the RJ45 connector to a serial connector. BNC and F-type connectors are used with coaxial cables. ST, SC, and LC connectors are used with fiber optic cables.

Connect pin 1 to pin 8, pin 2 to pin 7, pin 3 to pin 6, and pin 4 to pin 5.ExplanationWhen terminated with an RJ45 connector on both ends, the wires within the connectors are rolled over to the opposite connector as follows:• Pin 1 is connected to pin 8• Pin 2 is connected to pin 7• Pin 3 is connected to pin 6• Pin 4 is connected to pin 5A crossover cable uses the T568A standard on one end and the T568B standard on the other end. The crossover cable connects pin 1 with pin 3 and pin 2 to pin 6. Connecting each pin to the same pin on the other end creates a straight-through cable.

222.55.0.0192.15.5.55223.16.5.0ExplanationThe following are Class C addresses: 192.15.5.55, 222.55.0.0, and 223.16.5.0. The first octet of Class C addresses is in the range of 192 to 223.

132.70.254.15ExplanationAddresses starting with 127 are reserved and cannot be assigned to hosts. The address 199.45.207.0 is a network ID, and is therefore not assigned to a host.

SupernettingExplanationThe subnet address 198.162.1.0/23 is an example of a supernetted address. With supernetting, multiple smaller subnets are combined into a single larger subnet. Supernetting is performed by taking the default subnet mask and making it smaller (using less bits). For this address, the default subnet mask uses 24 bits (255.255.255.0). With supernetting, the mask is altered to use only 23 bits (255.255.254.0) to combine multiple subnets together. Subnetting is the process of dividing a larger network into smaller networks. With the subnet address in this example, a subnetted address would use a larger subnet mask (using more bits). A subnetted address might use 25 bits (255.255.255.128) or more to subdivide the network into multiple smaller subnets. Sometimes the term subnetting can be used to refer to both subnetting and supernetting, but in this example, supernetting better describes what is being done. Classful addressing uses the default subnet mask based on the address class. If classful addressing were used, the subnet would use a 24 bit mask. Private addresses are within the following ranges:• 10.0.0.1 to 10.255.255.254• 172.16.0.1 to 172.31.255.254• 192.168.0.1 to 192.168.255.254

Class A, Class B, Class B, Class CExplanationThe IP addresses listed are of the following classes: Class A, Class B, Class B, Class C. You can identify the IP address class by memorizing the range of values for the first octet.• 0-126 = Class A• 128-191 = Class B• 192-223 = Class C• 223-239 = Class D• 240-255 = Class E

166.70.255.254ExplanationThe last address you can assign to hosts on the 166.70.0.0 network is 166.70.255.254. The network address is a Class B address and uses a default subnet mask of 255.255.0.0. The last two octets are used for host addresses. 166.70.0.0 cannot be used as a host address because it is the network address. 166.70.255.255 cannot be used as a host address because it is the broadcast address.

129.11.99.78/16ExplanationUse 129.11.99.78/16 for the address and the mask. With CIDR notation, follow the IP address with a slash (/) and the number of bits in the mask. The default subnet mask for this address is 255.255.0.0 which uses 16 bits in the mask.A mask value of 255.0.0.0 uses 8 bits, and a mask value of 255.255.255.0 uses 24 bits.

200.78.151.111200.78.151.12200.78.151.252ExplanationAll hosts on this network must share the first three octets of the IP address (200.78.151). Youcannot assign 200.78.151.0 to a host because this address indicates the address of the network. You cannot assign 200.78.151.255 because this address is reserved for the broadcast address.

Subnets divide an IP network address into multiple network addresses.ExplanationSubnets divide an IP network address into multiple network addresses. This allows you to haveseveral smaller networks while using only one network address.

145.8.260.7257.0.122.55ExplanationIP addresses have a value between 0 and 255 within each octet. In this list, 45.22.156.256, 145.8.260.7, and 257.0.122.55 are not valid IP addresses.

206.58.170.67Explanation206.58.170.67 is the decimal form of the IP address. To convert binary to decimal, remember the following numbers: 128, 64, 32, 16, 8, 4, 2, 1Each number represents the decimal value for a binary 1 in the corresponding position. For example, 10000000 is equal to 128, and 00010000 is equal to 16. To find the decimal form of a binary number, add up each decimal equivalent for each 1 bit in the address. For example, the number 11001110 would be: 128 + 64 + 8 + 4 + 2 = 206.

211.70.0.254ExplanationThe last address you can assign to hosts on the 211.70.0.0 network is 211.70.0.254. The network address is a Class C address and uses a default subnet mask of 255.255.255.0. The last octet is used for host addresses. 211.70.0.0 cannot be used as a host address because it isthe network address. 211.70.0.255 cannot be used as a host address because it is the broadcast address.

255.255.255.0ExplanationIP addresses are divided into classes. The most common of these are classes A, B, and C. Each address class has a different default subnet mask. To identify the class of an IP address, look at its first octet.• Class A networks use a default subnet mask of 255.0.0.0 and have 0-126 as their first octet.• Class B networks use a default subnet mask of 255.255.0.0 and have 128-191 as their first octet.• Class C networks use a default subnet mask of 255.255.255.0 and have 192-223 as their first octet.In this question, the IP address falls in the Class C range and therefore has a default subnet mask of 255.255.255.0.

10000011.00001001.11001010.01101111Explanation10000011.00001001.11001010.01101111 is the binary format of the address. To convert binary to decimal, remember the following numbers:128, 64, 32, 16, 8, 4, 2, 1 Each number represents the decimal value for a binary 1 in the corresponding position. For example, 10000000 is equal to 128, and 00010000 is equal to 16.To find the binary form of a decimal number, try to subtract each decimal value from the valuein the octet. For example, for 131, you can subtract 128 leaving a remainder of 3. You can then subtract 2 and then 1. For each number you can subtract, write a 1 in the binary position of the address.

100.55.255.255ExplanationThe broadcast address for the subnet is the last address on the subnet. In this example, the address uses 16 bits in the subnet mask (255.255.0.0), meaning that the first two octets indicate the subnet address (100.55.0.0), and the last two octets are used for host addresses.The last possible address on this subnet is 100.55.255.255.

129.0.0.1168.16.5.1191.168.2.15ExplanationIP addresses are divided into classes. The most common of these are classes A, B, and C. Each address class has a different default subnet mask. To identify the class of an IP address, look at its first octet.• Class A networks use a default subnet mask of 255.0.0.0 and have 0-126 as their first octet.• Class B networks use a default subnet mask of 255.255.0.0 and have 128-191 as their first octet.• Class C networks use a default subnet mask of 255.255.255.0 and have 192-223 as their first octet.In this question, the IP addresses that fall in the Class B IP address range are 191.168.2.15, 129.0.0.1, and 168.16.5.1.

Combine different media type on to the same subnet.ExplanationSubnets cannot be used to combine networks of different media type on to the same subnet. Each network with a distinct media type has its own subnet. Subnets can be used to combine networks with different media types within the same internetwork.

166.70.0.1ExplanationThe first address you can assign to hosts on the 166.70.0.0 network is 166.70.0.1. The network address is a Class B address and uses a default subnet mask of 255.255.0.0. The last two octets are used for host addresses. The host address range is 166.70.0.1 to 166.70.255.254.166.70.0.0 cannot be used as a host address because it is the network address. 166.70.255.255 cannot be used as a host address because it is the broadcast address.

255.0.0.0ExplanationThe default subnet mask for this address is 255.0.0.0. The address is a class A address, which begins with a number between 1 and 126 in the first octet. 21.0.0.0 is the subnet address. 255.255.0.0 is the default subnet mask for a class B address,and 255.255.255.0 is the default subnet mask for a class C address.

172.16.1.262.2.2.2ExplanationA valid IPv4 address consists of 4 8bit (1 byte) numbers separated by periods. For example, 10.0.0.65. Because they are 8 bits long, these numbers are frequently called octets. Even though we typically express these numbers using decimal notation, it's important to remember that these numbers are binary numbers. The lowest value one of these numbers can have is 00000000. The decimal equivalent for this number is simply 0. The highest value one these numbers can take is 11111111. The decimal equivalent of this number is 255. Therefore, in decimal notation, each octet must contain a number between 0 and 255inclusively.

132.12.0.0129.0.0.0190.65.2.0ExplanationThe following are Class B addresses: 129.0.0.0, 132.12.0.0, and 190.65.2.0. The first octet of Class B addresses is in the range of 128 to 191.

130.16.61.3ExplanationIf you plan to use the Class B address for all nodes on the network, the nodes must all havethe same network address. In this case, all IP addresses must begin with 130.15.

255.255.0.0ExplanationWith CIDR notation, the number of bits in the subnet mask is indicated by the /16 following the IP address. A mask that uses 16 bits is written 255.255.0.0 in decimal format. Each octet in the mask uses 8 bits, so a mask with 16 bits uses two full octets. Use /8 for the mask 255.0.0.0 and /24 for the mask 255.255.255.0. In this example, a /24 mask would be the default subnet mask, but the address is using a nondefaultmask of 255.255.0.0.

179.113.89.0179.113.0.118179.113.65.12ExplanationAll hosts on this network must share the first two octets of the IP address (179.113). You cannot assign 179.113.0.0 to a host because this address indicates the address of the network.

114.58.12.0114.122.66.12114.0.0.15ExplanationWith a Class A network, the first octet indicates the network address. All hosts on the network must have the same value in the first octet (114).

169.254.0.1 169.254.255.254ExplanationThe Internet Assigned Numbers Authority (IANA) has reserved 169.254.0.1 through 169.254.255.254 for Automatic Private IP Addressing (APIPA). APIPA also sets the subnet mask on the network to 255.255.0.0.

255.255.0.0169.254.0.0ExplanationAutomatic Private IP Addressing (APIPA) uses a network address of 169.254.0.0 with the default Class B subnet mask of 255.255.0.0. Host addresses will be within the range of169.254.0.1 and 169.254.255.254.

DHCPExplanationYou can use the Dynamic Host Configuration Protocol (DHCP) to set up a DHCP server that will assign IP addresses automatically to network hosts. DHCP servers will not assign the same IP address to two different hosts.

DHCP serverExplanationUse a DHCP server to deliver configuration information to hosts automatically. Using DHCP is easier than configuring each host manually.Use a gateway to provide access to a different network, or to a network using a different protocol. Use a router to connect multiple subnets. Use a DNS server to provide name resolution, for example to get the IP address associated with a logical host name.

Use Automatic Private IP AddressingInstall a DHCP server on the networkExplanationTo avoid duplicate IP addresses being used by network systems, automatic IP assignment is used. Both the DHCP service and APIPA can automatically assign addresses to client systems. Clients configured to use static IP addressing may inadvertently have duplicate IP addressesassigned to them. In such a case, one of the systems will not be able to log on to the network.

A DHCP server assigns addresses to requesting hosts.It can deliver other configuration information in addition to IP addresses.ExplanationDHCP servers deliver IP addresses as well as other host configuration information to network hosts. DHCP can be configured to assign any available address to a host, or it can assign a specific address to a specific host.

DNS ExplanationDNS is a system that is distributed throughout the internetwork to provide address/name resolution. For example, the name www.mydomain.com would be identified with a specific IP address. ARP is a protocol for finding the IP address from a known MAC address. DHCP is a protocol used to assign IP addresses to hosts. Telnet is a remote management utility.

DNS serverExplanationUse a DNS server to provide hostname-to-IP address resolution. A bandwidth shaper modifies the flow of traffic to keep traffic within predefined limits. A load balancer accepts incoming client requests, and distributes those requests to multiple other servers. An IDS detects security threats, while an IPS can both detect and respond to security threats.

Wait for convergence to take place.ExplanationWhen using a routing protocol, changes in routing information take some time to be propagated to all routers on the network. The term convergence is used to describe the condition when all routers have the same (or correct) routing information. Static routes in the routing table must be updated manually. Restarting RIP might actually increase the time required for changes to be learned. Forcing an update (if the router supports it) is not a requirement as the periodic sharing of routes will eventually update the routing tableentry.

RIP uses hop counts as the cost metric.ExplanationRIP is a distance vector routing protocol. As such, it is susceptible to the count-to-infinity problem. RIP uses the hop count as the cost metric. Because it has a limitation of 15 hops in one route, it is not suited for large networks.

EIGRPExplanationEIGRP is a hybrid routing protocol developed by Cisco for routing within an AS. RIP is a distance vector protocol, while OSPF and ISIS are link state protocols.

Manually reconfigure the default route to point to the new next hop router.ExplanationWith a static route, when changes to the network occur, routing table entries must be modified, added, or removed manually. In this example, the default route was configured manually, so must be manually updated. When using a routing protocol, routing changes are made automatically by routers sharing routing information. To make a change for a dynamic route, simply wait for convergence to occur (the term convergence describes the condition when all routers have the same routing information).

All routes must be manually updated on the router.ExplanationStatic routing requires that entries in the routing table are configured manually. Network entries remain in the routing table until manually removed. When changes to the network occur, static entries must be added or removed. The next hop router is used with most routes to identify the next router in the path to the destination, regardless of whether the route is a static or dynamically-learned route. The hop count can be used by static or dynamic routes, depending on the routing protocol used. Static routing can be used for private and public networks, whether connected to the Internet or not.

ClasslessExplanationBecause the IP address is not using the default subnet mask, it is using classless addressing. Classless addressing modifies the length of the subnet mask, using a custom mask value instead of the default subnet mask. Classful addressing uses the default subnet mask. Devices that only support classful addressing assume the subnet mask based on the IP address class. A broadcast address is an address that is sent to all hosts. Broadcast addresses are the last possible address on a subnet. A multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. Multicast addresses are in the range of 224.0.0.0 to 239.255.255.255. A public address is an address that is registered for use on the Internet.

OSPF requires an area 0, while ISIS does not.ExplanationLike OSPF, ISIS uses areas when designing the network. However, ISIS does not require anarea 0 like OSPF does. Because ISIS was originally designed for non-IP protocols, it can more easily support IPv6 routing.Both OSPF and ISIS have the following characteristics:• Both are link state protocols.• Both are classless protocols, supporting CIDR and VLSM.• Both are Interior Gateway Protocols (IGPs) that are used within an AS.

ClasslessVLSMExplanationClassless InterDomain Routing (CIDR) allows for non-default subnet masks (variable length subnet mask or VLSM). Routers use the following information to identify networks:• The beginning network address in the range• The number of bits used in the subnet maskFor example, the subnet 199.70.0.0 with a mask of 255.255.0.0 is represented as 199.70.0.0/16 (with 16 being the number of 1 bits in the subnet mask). Classful addresses rely on the IP address class to identify the subnet mask. Network Address Translation (NAT) allows you to connect a private network to the Internet without obtaining registered addresses for every host. Private addresses are translated to the public address of the NAT router. OSPF is a routing protocol that supports CIDR features.

ConvergenceExplanationThe term convergence is used to describe the condition when all routers have the same (or correct) routing information. Convergence requires some time, but once reached means that any router has learned about all other networks that are being advertised (or shared) on thenetwork. Link state and distance vector describe general methods that routers use to share routes with other routers. Classful describes a routing protocol that assumes the subnet mask based on the address class of the network. Variable

OSPF is a classless link-state routing protocol.ExplanationOSPF is a classless link-state routing protocol. RIP version 1 and IGRP are both classful distance vector routing protocols. EIGRP is a hybrid protocol that supports classless addressing.

RIPExplanationRIP networks are limited in size to a maximum of 15 hops between any two networks. A network with a hop count of 16 indicates an unreachable network. The other routing protocols do not use the hop count as the metric. EIGRP uses bandwidth and delay for the metric. OSPF and ISIS use a relative link cost. BGP uses paths, rules, and polocies for the metric.

The first router in the path to the destination network.ExplanationThe next hop router is the first (or next) router in the path to the destination network. Each router looks at the destination network in the packet, then consults the routing table to identify the next hop router to the destination network. The hop count identifies the number of routers in the path to the destination network. A default gateway router is a router that is used for packets used to external networks. Most routers do not have a default gateway setting, but instead use a default route setting which identifies a next hop router for all unknown networks.

OSPFExplanationOSPF divides a large network into areas. Each autonomous system requires an area 0 that identifies the network backbone. All areas are connected to area 0, either directly or indirectly through another area. Routes between areas must pass through area 0. ISIS uses areas but does not have an area 0 requirement. Neither RIP nor EIGRP use areas.

If the network is connected to the Internet using multiple ISPs.ExplanationVery large networks can use BGP internally, but typically only share routes on the Internet if the AS has two (or more) connections to the Internet through different ISPs. If your network has over 15 hops, use a routing protocol other than RIP. Use OSPF or ISIS to divide your network into areas. Private networks that use public IP addresses do not need to share routes with Internet routers? it is typically the responsibility of the ISP to configure routes into the private network, even when public addressing is being used. A single route out of the private network is all that is required if the network has a single connection to the Internet.

Drop the packet.ExplanationIf a packet does not match any route in a routing table, the router will simply drop the packet. In this example, the router does not know about the destination network, and also is not configured with a default route. With a default route, the router will forward the packet to thenext hop router specified by the default route.

Forward the packet to the next hop router specified by the route to network 0.0.0.0.ExplanationA route of 0.0.0.0 with a mask of 0.0.0.0 identifies a default route. The default route is usedwhen no other route is a better match. Packets that match no other networks are sent to thenext hop router specified by default route.

RIP is a classful protocol, while RIPv2 is a classless protocol.ExplanationRIP v1 is a classful protocol, meaning that the subnet mask is not included in routing updates. With RIP, only the default subnet mask is used to identify networks. RIP v2 is a classless protocol, meaning that the subnet mask is included in routing updates. RIPv2 supports variablelength subnet masks (VLSM). Both RIP and RIPv1 are distance vector protocols and use the hop count for the metric. RIP and RIPv2 have a limit of 15 hops between any two networks.

BGPExplanationBGP is the protocol used on the Internet: ISPs use BGP to identify routes between ASs. Very large networks can use BGP internally, but typically only share routes on the Internet if the AS has two (or more) connections to the Internet through different ISPs. RIP is used on small private networks, while OSPF and EIGRP are used on larger private networks. ISIS is used on very large private networks and within the Internet Service Provider (ISP) network.

OSPF & IS-ISExplanationBoth OSPF and ISIS are link state protocols. Using the link state method, routers share only their directly connected routes using special packets called link-state advertisements (LSAs) and link-state packets (LSPs). These route advertisements are flooded (forwarded) throughout the network. Routers use this information to build a topology database of the network. RIP and RIPv2 are classified as distance vector protocols. Using the distance vector method, routers share their entire routing table with their immediate neighbors. Routes learned fromneighboring routers are added to the routing table, then shared with that router's neighbors. EIGRP is a balanced hybrid protocol. A hybrid method combines characteristics of both the distance vector and link state methods. It shares its full routing table at startup, followed bypartial updates when changes occur.

IGPExplanationYou would use an Interior Gateway Protocol (IGP) on routers within your network. Routing protocols can be classified based on whether they are routing traffic within or between autonomous systems: An Interior Gateway Protocol (IGP) routes traffic within an AS? an Exterior Gateway Protocol (EGP) routes traffic between ASs. Link state and distance vector describe how routing protocols share routing information. The network size might determine which protocol is best for your network. Static routing uses manually defined routes in the routing table, while dynamic routing uses a protocol so routers learn and share routes with other routers. You can use either static or dynamic routing (or both) on a private network.

169.254.0.1 169.254.255.254Explanation169.254.0.1 169.254.255.254 is the range of IP addresses assigned to Windows DHCP clients if a DHCP server does not assign the client an IP address. This range is known as the Automatic Private IP Addressing (APIPA) range. The other three ranges listed in this question are defined as the private IP addresses from RFC 1918 which are commonly used behind a NAT server.

IANAExplanationThe Internet Assigned Numbers Authority (IANA) is responsible for allocating IP addresses used on the Internet. When you want to obtain a public IP address, you would typically get the address from your ISP, which has received it from a Regional Internet Registry (RIR), which has been assigned a block of addresses from IANA. IANA is operated by the Internet Corporation for Assigned Names and Numbers (ICANN), so you might also see that ICANN is responsible for assigning public IP addresses. The IETF is an organization that is responsible for settings standards used on the Internet. For example, the IETF has defined the standards for NAT as well as other protocols. The IEEE is an organization that sets networking standards such as for Ethernet or wireless networking. CompTIA is a professional organization that represents computing technology companies and individuals.

Private addresses are not accessible through the Internet.ExplanationThe server has been assigned a private IP address. Private addresses are not accessible from the Internet. Instead, a NAT router translates the private address into a public address, and the public address is used to gain access to the private host.

Public networkExplanationMost IP addresses are public IP addresses. However certain ranges have been reserved for private networks. These are:• 10.0.0.0 10.255.255.255• 172.16.0.0 172.31.255.255• 192.168.0.0 192.168.255.255Because your computer's IP address does not fall into these ranges, it is a public IP address.

PATExplanationPort address translation (PAT) associates a port number with the translated address. Use PAT to allow multiple private hosts to share a single public address. Each private host is associated with a unique port number.Technically speaking, NAT translates one address to another. With only NAT, you would have to have a public address for each private host. NAT would associate a single public address with a single private address. Because virtually all NAT routers perform port address translation, most routers that are configured with NAT are really performing PAT. When you use a NAT router, you are normally using PAT and not just NAT. (NAT is typically used synonymously with PAT.) Classless InterDomain Routing (CIDR) allows for non-default subnet masks (variable length subnet mask or VLSM).

172.18.188.67192.168.12.25310.0.12.15ExplanationOf the addresses listed here, the following are in the private IP address ranges:• 10.0.12.15 (private range = 10.0.0.0 to 10.255.255.255)• 172.18.188.67 (private range = 172.16.0.0 to 172.31.255.255)• 192.168.12.253 (private range = 192.168.0.0 to 192.168.255.255)

142.15.6.1ExplanationA public network is a network that does not limit traffic to members of a corporation or other group. The Internet is an example of a public network. Certain sets of IP addresses are reserved for private networks only and cannot be used on public networks. They are:• 10.0.0.0 to 10.255.255.255• 172.16.0.0 to 172.31.255.255• 192.168.0.0 to 192.168.255.255

Static NATExplanationStatic NAT maps an internal IP address to a static port assignment. Static NAT is typically used to take a server on the private network (such as a Web server) and make it available on the Internet. External hosts contact the internal server using the public IP address and the staticport. Using a static mapping allows external hosts to contact internal hosts. Dynamic NAT automatically maps internal IP addresses with a dynamic port assignment. On the NAT device, the internal device is identified by the public IP address and the dynamic port number. Dynamic NAT allows internal (private) hosts to contact external (public) hosts but not vice versa. External hosts cannot initiate communications with internal hosts. DNS records associate a host name with an IP address. With multicast, a single data stream can be forwarded to all computers that are members of the same multicast group.

141:0:0:0:15:0:0:16384:1319:7700:7631:446A:5511:8940:2552ExplanationAn IPv6 IP address is a 128-bit address listed as eight 16-bit hexadecimal sections. Leading zeros can be omitted in each section. Therefore, 6384:1319:7700:7631:446A:5511:8940:2552 and 141:0:0:0:15:0:0:1 are both valid IPv6 IP addresses. A single set of all zero sections canbe abbreviated with two colons (::). Therefore, 141::15:0:0:1 would also be a valid address.

FEC0::AB:9007ExplanationFEC0::AB:9007 is a valid IPv6 address. The :: in the address replaces blocks of consecutive 0's. The longer form of this address would be FEC0:0000:0000:0000:0000:0000:00AB:9007. Leading 0's within a quartet can also be omitted. You can only omit one block of 0's using the double colon. Each number in the IPv6 address must be between 0-9 or A-F? G is not a valid number for the IPv6 address. An address without double colons should have a total of 32 hexadecimal numbers in 8 blocks.

MulticastExplanationA multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. A unicast address is an address that identifies a single host. A broadcast address is an address that is sent to all hosts. Broadcast traffic is typically only forwarded within (but not between) a subnet. Simplex communication uses a single channel for both sending and receiving. Half-duplex uses a separate channel for sending and receiving, but the channels are shared by multiple devices and can only be used by a single device at a time.

MulticastExplanationThe address 232.111.255.250 is a multicast address. A multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. Multicast addresses are in the range of 224.0.0.0 to 239.255.255.255. A unicast address is an address that identifies a single host. A broadcast address is an address that is sent to all hosts. Broadcast addresses are the last possible address on a subnet(typically ending in 255). The private IPv4 address ranges are:• 10.0.0.1 to 10.255.255.254• 172.16.0.1 to 172.31.255.254• 192.168.0.1 to 192.168.255.254

UnicastExplanationA unicast address is an address that identifies a single host. A broadcast address is an address that is sent to all hosts. Broadcast traffic is typically only forwarded within (but not between) a subnet. A multicast address is an address that identifies a group of computers. Members of the group share the same multicast address. Simplex communication uses a single channel for both sending and receiving. Full-duplex has a dedicated send and receive channel between any two hosts.

IGMPExplanationIP hosts use the IGMP or Internet Group Management Protocol to inform multicast-enabled routers that they want to receive specific multicast frames.

UnicastExplanationThe address 198.162.12.254 is a unicast address that identifies a single host on the 198.162.12.0 subnet. 198.162.12.255 is the broadcast address for the subnet. Multicast addresses are in the range of 224.0.0.0 to 239.255.255.255.The private IPv4 address ranges are:• 10.0.0.1 to 10.255.255.254• 172.16.0.1 to 172.31.255.254• 192.168.0.1 to 192.168.255.254

PoEExplanationPower over Ethernet (PoE) supplies power to end devices through the RJ45 Ethernet switch port. Power to the phone is carried on unused wires within the drop cables. Spanning tree is a protocol on a switch that allows the switch to maintain multiple paths between switches within a subnet. The spanning tree protocol runs on each switch and is used to select a single path between any two switches. Trunking allows a switch to forward VLAN traffic between switches. 802.1x is an authentication protocol used with port security (or port authentication).

SIP & RTPExplanation Voice over IP (VoIP) uses the following protocols:• Real-Time Transport Protocol (RTP) packets contain the actual voice data.• Session Initiation Protocol (SIP) is used to set up, maintain, teardown, and redirect the call.NTP is used for synchronizing time between devices. SNMP is used by devices for sending configuration information. SMTP is used for sending email.

SIPExplanationThe Session Initiation Protocol (SIP) is used to set up, maintain, teardown, and redirect the call. The Real-TimeTransport Protocol (RTP) contains the actual voice data. SSH is used for secure remote administration of a network device. TLS is used to add security to other protocols. NTP is used for synchronizing clocks on network devices.

Virtual serversExplanationServer virtualization runs multiple instances of a server operating system on a single physical computer. With server virtualization, you can migrate servers on older hardware to newer computers, or add virtual servers to computers with extra unused hardware resources. Virtual desktops do not provide DHCP services. Virtual networks allow virtual servers and desktops to communicate with each other, and they can also allow communication (via the host operating system) to network devices out on the physical network. Network as a Service (NaaS) servers and desktops that are all virtualized and managed by a contracted third-party.

A hypervisor allows virtual machines to interact with the hardware without going through the host operating system.ExplanationA hypervisor is a thin layer of software that resides between the virtual operating system(s) and the hardware. A hypervisor allows virtual machines to interact with the hardware without going through the host operating system. A hypervisor manages access to system resourcessuch as:• CPU• Storage• RAMA physical machine (also known as the host operating system) has the actual hardware in place on the machine, such as the hard disk drive(s), optical drive, RAM, motherboard, etc. A virtual machine is a software implementation of a computer that executes programs like a physical machine. The virtual machine(s) appear to be a self-contained and autonomous system(s). A virtual hard disk (VHD) is a file that is created within the host operating system and that simulates a hard disk for the virtual machine.

Virtual switchExplanationVirtual switches allow multiple virtual servers and/or desktops to communicate on virtual network segments and/or the physical network. Virtual switches are often configured in the hypervisor. A virtual hard disk (VHD) is a file that is created within the host operating system and that simulates a hard disk for the virtual machine. A physical machine (also known as the host operating system) has the actual hardware in place on the machine, such as the hard disk drive(s), optical drive, RAM, motherboard, etc. A virtual desktop is a virtual machine in a software implementation of a computer that executes programs like a physical machine.

Full virtualizationExplanationIn full virtualization, the virtual machine completely simulates a real physical host. This allows most operating systems and applications to run within the virtual machine without being modified in any way. In partial virtualization, only some of the components of the virtual machine are virtualized. Be aware of the following:•The operating system uses some virtual components and some real physical hardware components in the actual device where the hypervisor • The operating system or application must be modified to run in a partial virtualization environment.In paravirtualization, the hardware is not virtualized. Be aware of the following:• All of the guest operating systems running on the hypervisor directly access various hardware resources in the physical device? components are not virtual. • The guest operating systems run in isolated domains on the same physical hardware.• The operating system or application must be modified before they can run in a paravirtualization environment.