Which cable do you use to connect a PC directly to the fast ethernet interface on a router. For example if you wanted to do an IOS upgrade from your laptop?

You always use a crossover cable to connect a PC/Server directly to the fast ethernet interface of a router.

Which subnet is host 192.168.1.67 /27 in?

This host is in 192.168.1.64

Which config register setting will allow the router to boot with a blank config enabling you to perform a password recovery?

0x2142 on most routers.

Which port number is used for POP 3 connections?

POP3 uses port number 110.

What speed must the baud rate connection be when you are setting up a hyperterminal connection to the console port on a router?

It is always 9600bps unless you are doing a

a disaster recovery uploading the image over

the console cable.

You want to send a ping across your WAN connection but source it from your LAN interface. How would you do that (which command)?

Type the 'ping' command but then press the enter key. You will be able to use extended commands and then choose to source the ping from a local IP address or interface.

A user on your network calls you to complain that they are trying to allocate an IP address to their PC but they keep getting an error message. The address is 192.168.1.23/29. What is the problem?

That is the broadcast address for the subnet!

You want to configure RIP version 2 on your router. Which command will tell the router that it is RIP version 2 you are using?

Router(config)#router rip Router(config-router)#version 2

Which command shows you RIP updates going out of and coming into your router?

debug ip rip

Which command will back up your routers startup config to a server on your network?

Router#copy start tftp: (you will then have to specify the tftp server address).

Which service resolves a hostname to an IP address?

DNS resolves a hostname to an IP address.

Classless means that the subnet informtion is sent out with the route updates and RIPv2 does this so it is classless.

The default encapsulation type on Cisco serial interfaces is what?

HDLC or more specifically Cisco HDLC

How does a router recognise a Class C address in its binary form?

The router sees the first three binary bits as 110

Write out the 7 layers of the OSI model starting with Application. What format is data in at each level?

Application - Data

Presentation - Data

Session - Data

Transport - Segment

Network - Packet

Data Link - Frame

Physical - Bits

WEP or Wired Equivalent Privacy is defined in which IEEE standard?

Describe the process of data encapsulation as data is processed from creation until it exits a physical interface to a network. Use the OSI model as an example.

Data encapsulation represents the process of a layer adding a header (and possibly a trailer) to the data as it is processed by progressively lower layers in the protocol specification. In the context of OSI, each layer could add a header so that, other than the true application data, there would be six other headers (Layers 2 to 7) and a trailer for Layer 2, with this L2PDU being encoded by the physical layer onto the network media.

Name some benifits of layering network protocol specifications.

Less complex

Standard Interfaces

Easier to learn

Earsier to develop

Multi-vendor interoperability

Modular engineering

What header or trailer does a router discard as a side effect of routing?

A router discards the data-link header and trailer as a side effect of routing. This is because the network layer, where routing is defined, is interested in delivering the network layer (Layer 3) PDU from end to end. Routing uses intermediate data links

What OSI layer typically encapsulates using both a header and a trailer?

The data link layer typically encapsulates using both a header and a trailer. The trailer typically includes a frame check sequence (FCS), which is used to perform error detection.

What terms are used to describe the contents of the data encapsulated by the data link, network, and transport layers, respectively?

Frame, packet, and segment, respectively.

Explain the meaning of the term L5PDU.

PDU stands for protocol data unit. A PDU is the entity that includes the headers and trailers created by a particular networking layer, plus any encapsulated data. For instance, an L5PDU includes Layer 5 headers and the encapsulated data.

Explain how Layer x on one computer communicates with Layer x on another computer.

Each layer of a networking model works with the same layer on another computer with which it wants to communicate. The protocol defined by each layer uses a header that is transmitted between the computers to communicate what each computer wants to do.

List the terms behind the acronym TCP/IP.

Transmission Control Protocol and Internet Protocol.

Open System Interconnection.

What is the main purpose(s) of Layer 2?

Layer 2 (the data link layer) defines addressing specific to a particular medium as part of the means of providing delivery of data across that medium. It also includes the protocols used to determine what device(s) accesses the media at any point in time.

Layer 1 (the physical layer) is responsible for encoding energy signals onto the medium and interpreting a received energy signal. Layer 1 also defines the connector and cabling details.

What does MAC stand for?

MAC stands for Media Access Control.

Name three terms popularly used as a synonym for MAC address.

NIC address, card address, LAN address, hardware address, Ethernet address, and burned-in address are all synonymous with MAC address. All of these names are used casually and in formal documents, and they refer to the same 6-byte MAC address

concept as defined by IEEE.

What is the purpose of a wireless service set identifier (SSID)?

The SSID attaches a code to each IP packet to identify it as belonging to that network.

What portion of a MAC address encodes an identifier representing the manufacturer of the card?

The first 3 bytes, called the Organizationally Unique Identifier (OUI), comprise the portion of a MAC address that encodes an identifier representing the manufacturer of the card.

Are MAC addresses defined by a Layer 2 or Layer 3 protocol?

MAC addresses are defined by a Layer 2 protocol. Ethernet MAC addresses are defined in the 802.3 specification.

How many bits are present in a MAC address?

MAC addresses have 48 bits. The first 24 bits for burned-in addresses represent a code that identifies the manufacturer.

Name the two main parts of a MAC address. Which part identifies which “group” this address is a member of?

There are no parts, and nothing defines a grouping concept in a MAC address. This is a trick question. Although you might have guessed that the MAC address has two parts—the first part dictated to the manufacturer, and the second part made up by the manufacturer—there is no grouping concept.

What OSI layer typically encapsulates using both a header and a trailer?

The data link layer typically encapsulates using both a header and a trailer. The trailer typically includes a frame check sequence (FCS), which is used to perform error detection.

If a Fast Ethernet NIC currently is receiving a frame, can it begin sending a frame?

Yes, if the NIC is operating in full-duplex mode.

What are the two key differences between a 10-Mbps NIC and a 10/100-Mbps NIC?

The obvious benefit is that the 10/100-Mbps NIC can run at 100 Mbps. The other benefit is that 10/100-Mbps NICs can autonegotiate both speed and duplex between itself and the device that it is cabled to, typically a LAN switch.

Which commands identfies the internal NAT interface on the router?

You need to type 'ip nat inside' or 'ip nat outside' in interface configuration mode to tell the router that it is a NATint interface and if it inside or outside.

Your client has been given address 192.168.1.0

and requires four subnets and each subnet must be able to provide at least 10 hosts. Which subnet mask will reach this requirement?

255.255.255.192

Define the difference between broadcast and multicast MAC addresses.

Both identify more than one device on the LAN. Broadcast always implies all devices on the LAN, whereas multicast implies some subset of all devices. Devices that intend to receive frames addressed to a particular multicast address must be aware of the particular multicast address(es) that they should process. These addresses are dependent on the applications used. For example, the broadcast address is FFFF.FFFF.FFFF, and one sample multicast address is 0100.5e00.0001.

Explain the function of the loopback and collision-detection features of an Ethernet NIC in relation to half-duplex and full-duplex operations.

The loopback feature copies the transmitted frame back onto the receive pins on the NIC interface. The collision-detection logic compares the received frame to the transmitted frame during transmission; if the signals do not match, a collision is

occurring. With full-duplex operation, collisions cannot occur, so the loopback and collision-detection features are purposefully disabled, and concurrent transmission and reception is allowed.

Are DLCI addresses defined by a Layer 2 or Layer 3 protocol?

DLCI addresses are defined by a Layer 2 protocol. Although they are not covered in detail for this book, Frame Relay protocols do not define a logical addressing structure that can usefully exist outside a Frame Relay network; by definition, the addresses would be OSI Layer 2–equivalent.

Define the terms DCE and DTE in the context of the physical layer and a point-to-point serial link.

At the physical layer, DTE refers to the device that receives clocking from the device on the other end of the cable on a link. The DCE supplies that clocking. For example, the computer is typically the DTE, and the modem or CSU/DSU is the DCE. At the data link layer, both X.25 and Frame Relay define a logical DTE and DCE. In this case, the customer premises equipment (CPE), such as a router and a CSU/DSU, is the logical DTE, and the service provider equipment (the Frame Relay switch and

the CSU/DSU) is the DCE.

Which layer or layers of OSI are most closely related to the functions of Frame Relay? Why?

OSI Layer 2. Frame Relay depends on other well-known physical layer specifications. Frame Relay does define headers for delivery across the Frame Relay cloud, making it a Layer 2 protocol. Frame Relay does not include any routing or logical addressing specifications, so it is not a Layer 3 protocol.

True or false: “A leased line between two routers provides a constant amount of bandwidth—never more and never less.” Defend your answer.

True. A leased line creates the cabling equivalent of having a cable between the two routers, with the speed (clock rate) defined by the telco. Even when the routers have no data to send, the full bandwidth is available to be used.

Do HDLC and PPP, as implemented by Cisco routers, support Protocol Type fields and error detection? Explain your answer.

Both protocols support a Protocol Type field and an FCS field to perform error detection. PPP defines both fields as part of the PPP standard; the HDLC standard includes the FCS field, but Cisco added a Protocol Type field to the standard HDLC header.

What are some of the main similarities between Frame Relay and ATM?

Both use an access link to access the service provider. Both use the concept of a virtual circuit between DTE devices. And both allow multiple VCs to cross a single access link.

What are the two main functions of each OSI Layer 3–equivalent protocol?

Path selection, which is also called routing, and logical addressing.

Assume that PC1 sends data to PC2, and PC2 is separated from PC1 by at least one router. Are the IP addresses of the PCs in the same IP subnet? Explain your answer.

They must be in different subnets. IP addressing rules require that IP hosts separated by a router be in different subnets.

How many bits are present in an IP Version 4 address?

IPv4 addresses have 32 bits: a variable number in the network portion, and the rest of the 32 in the host portion. IP Version 6 uses a 128-bit address.

Name the two main parts of an IP address. Which part identifies which group this address is a member of?

Network and host are the two main parts of an IP address. When subnetted, there are three portions of the IP address: network, subnet, and host. However, because most people think of the network and subnet portions as one portion, another correct answer to this question, using popular terminology, would be subnet and host. In short, without subnetting, the network part identifies the group; with subnetting, the network and subnet part together identifies the group.

PC1 sends data to PC2 using TCP/IP. Three routers separate PC1 and PC2. Explain why the statement “PC1 sends an Ethernet frame to PC2” is true or false.

The statement is false. Packets are delivered from end to end across a network, whereas frames simply pass between devices on each common physical network. The intervening routers discard the original Ethernet header, replacing it with other datalink

headers as needed. A truer statement would be “PC1 sends an IP packet to PC2.”

In IP addressing, how many octets are in 1 byte?

One. Octet is a generic word to describe a single byte. Each IP address is 4 bytes, or four octets, long.

Describe the differences between a routed protocol and a routing protocol.

The routed protocol defines the addressing and Layer 3 header in the packet that actually is forwarded by a router. The routing protocol defines the process of routers exchanging topology data so that the routers know how to forward the data. A router uses the routing table created by the routing protocol when choosing where to route a packet.

Imagine an IP host on an Ethernet, with a single router attached to the same segment. In which cases does an IP host choose to send a packet to this router instead of directly to the destination host, and how does this IP host know about that single router?

Typically an IP host knows to what router to send a packet based on its configured default router. If the destination of the packet is in another subnet, the host sends the packet to the default router. Otherwise, the host sends the packet directly to the destination host because it is in the same subnet and, by definition, must be on the same data link.

A number that identifies a group of addresses, the interface out which to forward the packet, and the Layer 3 address of the next router to send this packet to are three items that you will always find in a routing table entry. For instance, IP routes contain subnet numbers, the outgoing interface, and the IP address of the next-hop

router.

Name the parts of an IP address when subnetting is used.

Network, subnet, and host are the three parts of an IP address. However, many people commonly treat the network and subnet parts of an address as a single part, leaving only two parts, the subnet and host parts. On the exam, the multiple-choice format should provide extra clues as to which terminology is used.

How many valid IP addresses exist in an unsubnetted Class A network?

16,777,214, derived by the formula 2

²⁴ – 2.

How many valid IP addresses exist in an unsubnetted Class B network?

65,534, derived by the formula 2

¹⁶– 2.

How many valid IP addresses exist in an unsubnetted Class C?

254, derived by the formula 2

⁸ – 2.

What values can a Class A network have in the first octet?

1 through 126, inclusive.

What values can a Class B network have in the first octet?

128 through 191, inclusive.

What values can a Class C network have in the first octet?

192 through 223, inclusive.

When subnetting a Class B network, do you create the network part of the address or the host part?

When subnetting a Class B network, using the entire third octet for the subnet part, describe the number of possible subnets created.

The subnet part consists of a full octet, which is 8 bits long. You can number 2⁸ things with 8 bits, or 256.

When subnetting a Class A network using the entire second octet for the subnet part, describe the number of hosts in each subnet.

The host part consists of two entire octets in this case, which is 16 bits long . You can number 2

When a router hears about multiple routes to the same subnet, how does it choose which route to use?

Routing protocols use a metric to describe how good each route is. The lower the metric is, the better the route is.

What is the primary purpose of a routing protocol?

Routing protocols discover the routes in a network and build routing tables.

True or false: “Routing protocols are required to learn routes of directly connected subnets.”

False. Routers add routes to directly connected subnets when the interfaces initialize. No routing protocols are needed.

List the similarities and differences between ARP and DNS.

Both protocols send messages with one piece of information, hoping to learn another piece of information. The similarities do not go beyond that fact. DNS requests are unicast IP packets sent specifically to the DNS server, whereas ARP uses a LAN broadcast frame. DNS queries supply a name, expecting to hear the corresponding IP address back from the server. ARP requests supply an IP address, hoping to hear a corresponding MAC address not from a server, but from the host that uses that IP address.

Describe the features required for a protocol to be considered connectionless.

Connectionless protocols allow communication to occur without any previous configuration or dynamic protocol messages between the two devices.

Describe the features required for a protocol to be considered connection oriented.

Either the protocol must exchange messages with another device before data is allowed to be sent, or some pre-established correlation between the two endpoints must be defined. TCP is an example of a connection-oriented protocol that exchanges messages before data can be sent; Frame Relay is a connection-oriented protocol for which a pre-established correlation between endpoints is defined.

In a particular error-recovering protocol, the sender sends three frames, labeled 2, 3, and 4. On its next sent frame, the receiver of these frames sets an Acknowledgment field to 4. What does this typically imply?

Frames through number 3 were received successfully. The receiver might have not received Frame 4, or Frame 4 might not have passed the FCS check.

Describe how TCP performs error recovery. What role do the routers play?

TCP numbers the first byte in each segment with a sequence number. The receiving host uses the Acknowledgment field in segments that it sends back to acknowledge receipt of the data. If the receiver sends an acknowledgment number that is a smaller number than the sender expected, the sender believes that the intervening bytes were lost, so the sender resends them. The router plays no role unless the TCP connection ends in the router—for example, a Telnet into a router.

How many TCP segments are exchanged to establish a TCP connection? How many are required to terminate a TCP connection?

A three-way connection-establishment sequence is used, and a four-way connection-termination sequence is used.

Describe the purpose of the Port Number field in a TCP header. Give one example.

The port numbers are used to help computers multiplex received data. For instance, a PC with two web browsers open.

How many UDP segments must be sent to establish a UDP connection? How many are used with normal UDP connection termination?

UDP does not establish connections because it is not connection oriented.

You want to prevent your router summarizing your

192.168.1.2 /30 network at the major network boundary. Which command will prevent the router from doing this?

Router(config-router)#no auto-summary

On a computer that receives data over a network, the process in which the device interprets the lower-layer headers and, when finished with each header, removed the header, revealing the next-higher-layer PDU.

It is the upper sub-layer of the Data Link Layer in the OSI reference model. It provides multiplexing and flow control that make it possible for several network protocols (IP, IPX) to coexist within a multipoint network and to be transported over the same network media. It acts as an interface between the Media Access Control (MAC) sublayer and the network layer. It is the same for the various physical media (such as Ethernet, token ring, and WLAN.

What's the difference between the 568A and 568B standard of Ethernet cabling pinouts?

568A describes pins 1 (g/w), 2 (green) as pair 3 and pins 3 (o/w), 6 (orange) as pair 2.  The reverse is true on 568B.  Either way, if a cable has two of same connector types, its a straight-thru cable and connects dissimilar items (pc to hub) whereas if it uses two different types, its a crossover cable and connects similar items (switch to switch).

Name the eight fields in an Ethernet frame and their function.

Preamble - Synchronization

Start Frame Delimiter (SFD) - signifies that the next byte beings the Destination MAC field

Destination MAC Address - Identifies the intended recipient of the frame

Source MAC Address - Identifies the sender of this frame

Length - Defines the length of the data field of the frame (either length or type is present, but not both).

Type - Defines the type of protocol listed inside the frame (either length or type ispresent, but not both)

Data and Pad - Holds data from a higher layer, typically an L3PDU and often an IP packet.

Frame Check Sequence (FCS) - Provides a method for the receiving NIC to determine if the frame experienced transmission errors.

The cable between the CSU/DSU and the telco CO typically users what type of connector to the CSU/DSU?

Channel Service Unit/Digital Service Unit.  A device that understands the Layer 1 details of serial links installed by a telco and how to use a serial cable to communicate with networking equipment such as routers.

1.544 Mbps

 (24 DS0's)

or

(24x64kbps)+8 kpbs overhead

44.736Mbps

(28 DS1's plus overhead)

2,048 Mbps

(32 DS0s)

34.064 Mbps

(16 E1s, plus overhead)

2.048 Mbps

(32 DS0s; Japanese standard)

The 10-Mbps baseband Ethernet specification using two pairs of twisted-pair cabling (Categories 3, 4, or 5): One pair transmits data and the other receives data. 10BASE-T, which is part of the IEEE 802.3 specification, has a distance limit of approximately 100m (328 feet) per segment.

A name for the IEEE Fast Ethernet standard that uses two-pair copper cabling, a speed of 100 Mbps, and a maximum cable length of 100 meters.

A name for the IEEE Gigabit Ethernet standard that uses four-pair copper cabling, a speed of 10000 Mbps (1Gbps), and a maximum cable length of 100 meters.

The IEEE standard for wireless LANs using the U-NII spectrum, OFDM encoding, at speed of up to 54 Mbps.

The IEEE standard for wireless LANs using the ISM spectrum, DSSS encoding, and speeds of up to 11 Mbps.

The IEEE standard for wireless LANs using the ISM spectrum, OFDM or DSSS encoding, and speeds of up to 54 Mbps.

The IEEE standard for wireless LAN security, including authentication and encryption.

A LAN network desing tern that refers to a switch interface connected to end-user devices.

access link

In Frame Relay, the phyical serial link that connects a Frame Relay DTE device, usually a router, to a Frame Relay switch.  The access link uses the same phyical layer standards as do point-to-point leased lines.

A wireless LAN device that provides a means for wireless clients to send data to each other and to the rest of a wired network, with the AP connecting to both the wireless LAN and the wired Ethernet LAN.

In security, the recording of access attempts.  Part of the AAA process.

In wireless LANs, a method or mode of operation in which clients send data directly to each other without the use of a wireless access point (AP).

The general topic of how on one computer, two adjacent layers in a networking architectural model work together, with the lower layer providing services to the higher layer.

In Cisco routers, a means for one router to choose between multiple routs to reach the same subnet when those routes were learned by different routing protocols.  The lower the administrative distance, the better the source of the routing information.

Asymmetric digital subscriber line.  One of many DSL technologies, ADLS is designed to deliver more bandwidth downstream (from the central office to the customer site) than upstream.

The term used by Cisco to refer to a variety of security tools that help prevent various attacks, including antivirus, anti-phishing, and anti-spam.

Address Resolution Protocol.  An Internet protocol used to map an IP address to a MAC address.  Defined in RFC 826

A feature of many Internet access technologies, including DSL, cable, and modems, in which the downstream transmission rate is higher that the upstream transmission rate.

The lack of an imposed time ordering on a bit stream.  Practically, both sides agree to the same speed, but there is no check or adjustment of the rates if they are slightly different.  However, because only 1 byte per transfer is sent, slight difference in clock speed are not an issue.

All ports on the root bridge are known as ___ ports?

Designated

Asynchronous Transfer Mode.  the international standard for cell relay in which multiple service types (such as voice, video, and data) are conveyed in fixed-length (53-byte) cells.  Fixed-length cells alow cell processing to occur in hardware, thereby reducing transit delays.

In security, the verification of the identity of a person or a process.

In security, the determination of the rights allowed for a particular user of device.

An internetwork in the administrative control of one organization, company, or governmental agency, inside which that organization typically runs an Interior Gateway Protocol (IGP).

A physical connector on a router that is designed to be used to allow a remote terminal, or PC with terminal emulator, to access a router using an analog modem.

A serial link between two routers, created without CSU/DSUs, by connecting a DTE cable to one router and a DCE cable to the other.  Typically used in labs to build serial links without the expense of an actual leased line from the telco.

A term that refers to a general type of routing protocol algorithm, the other two being distance vector and link state.  The Enhanced Interior Gateway Routing Protocol (EIGRP) is the only routing protocol that Cisco classifies as using a balanced hybrid alogorithm.

A reference to the speed of a networking link.  Its origins come from earlier communications technology in which the range, or width, of the frequency band dictated how fast communications could occur.

A Boolean AND between two numbers of the same length in which the first bit in each number is ANDed, and then the second bit in each number, and then the third, and so on.

A math operation performed on a pair of one-digit binary numbers.  The result is another one-digit number.  1 AND 1 yields 1; all other combinations yield a 0.

The low-order 4 bits of the configuration register in a Cisco router.  The value in the boot field in part tells the router where to look for a Cisco IOS image to load.

Basic Rate Interface.  An ISDN interface composed of two 64-kbps bearer (B) channels and one 16-kbps data (D) channel for circuit switched communication of voice, video, and data.

A special address in each subnet, specifically the largest numberic address in the subnet, designed so that packets sent to this address should be delivered to all hosts in that subnet.

A set of all devices that receive broadcast frames originating from any device within the set.  Devices in the same VLAN  are in the same broadcast domain.

An Ethernet frame sent to destination address FFFF.FFFF.FFFF, meaning that the frame sould be delivered to all hosts on the LAN

When subnetting a Class A, B, or C netowrok, the one subnet in each classful network for which all subnet bits have a value of binary 1.  The subnet broadcast address in this subnet has the same numeric value as the classful network's network-wide broadcast address.

A common physical signal path composed of wire or other media across which signals can be sent from on epart of a computer to another.

Cisco Discovery Protocol.  A media and protocol independent device-discovery protocol that runs on most Cisco-manufactured equipment, including routers, access servers, and switches.  Using CDP, a device can advertise its existence to other decives and receive information about other devices on the same LAN or on the remote side of a WAN.

A device on the other end of some communications cable that is advertising CDP updates.

A shorter way to write a subnet mask in which the number of binary 1s in the mask is simply written in decimal.  For instance, /24 denotes the subnet mask with 24 binary 1 bits in the subnet mask.  The number of bits of value binary 1 in the mask is considered to be the prefix length.

A generic reference to network services, typically WAN services, in which the provider sets up a (layer 1) circuit between two devices, and the provider makes no attempt to interpret the meaning of the bits.

An IPv4 Class A, B, or C network; called a classful network because these networks are defined by the class rules for IPv4 addressing.

Does not transmit the mask information along with the subnet number, and therefore must consider Class A, B, and network boundaries and perform autosummarizatoin at those boundaries.  Does not support VLSM.

An inherent characteristic of a routing protocol, specifically that the routing protocol does send subnet masks in its routing updates, thereby removing any need to make assumptions about the addresses in a particular subnet or network, making it able to support VLSM and manual route summarization.

Command-line interface.  An interface that enables the user to interact with the operation system by entering commands and optional arguments.

The speed at which a serial link encodes bits on the transmission medium.

The device to which the other devices on the link adjust their speed when using synchronous links.

The process of supplying a signal over a cable, either on a separate pin on a serial cable or a part of the signal transitions in the transmitted signal, so that the receiving device can keep synchronization with the sending device.

Coder-decoder.  An integrated circuit device that transforms analog voice signals into a digital bit stream and then transforms digital signals back into analog voice signals.

A set of network interface cards (NICs) for which a frame sent by one NIC could result in a collision with a frame sent by any other NIC in the same collision domain.

A part of the Cisco IOS Software CLI in which the user can type configuration commands that are then added to the device's currently used configuration file (running-config).

In ethernet switching, anything less than 64 bytes is called a "___" frame.

Runt

In Cisco routers, a 16-bit, user-configurable value that determines how the router functions during initialization.  In software, the bit position is set by specifying a hexadecimal value using configuration commands.

The process by which a connection-oriented protocol creates a connection.  With TCP, a connection is established by a three-way transmission of TCP segments.

A physical socket on a router or switch to which a cable can be connected bewteen a computer and ther router/switch, for the purpose of allowing the computer to use a terminal emulator and use the CLI to configure, verify, and troubleshoot the router/switch.

The time required for routing protocols to react to changes in the network, removing bad routes and adding new, better routes so that the current best routes are in all the routers' routing tables.

Customer premises equipment.  Any equipment related to communications that is located at the customer site, as opposed to inside the telephone company's network.

An Ethernet cable that swaps the pair used for transmission on one device to a pair used for receiving on the device on the opposite end of the cable  In 10BASE-T and 100BAWE-TX networks, this cable swaps the pair at pins 1,2 to pins 3,6 on the other end of the cable, and the pair at pins 3,6 to pins 1,2 as well.

Carrier sense multiple access with collision avoidance.  A media-access mechanism that defines how devices decide when they can send, with a goal of avoiding collisions as much as possible.  IEEE WLANs use CSMA/CA.

Carrier sense multiple access collision detect.  A media-access mechanism in which devices ready to transmit data first check the channel for a carrier.  If no carrier is sensed for a specific period of time, a device can transmit.  If two devices transmit a once, a collision occurs and is detected by all colliding devices.  This collision subsequently delays retransmissions from those devices for some random length of time.

Channel service unit/digital service unit.  A device that understands the Layer 1 details of serial links installed by a telco and how to use a serial cable to communicate with networking equipment such as routers.

You want to view the ARP entries stored on your router. Which command do you enter?

Router#show arp

Name the three types of Denial of Service (DOS) attacks?

Destroyers, crashers and flooders.

One of three options for internal processing on some models of Cisco LAN switches in which the frame is forwarded as soon a possible, including forwarding the first bits of the frame before the whole frame is received.

Data communications equipment.  From a physical layer perspective, the device providing the clocking on a WAN link, typically a CSU/DSU, is the DCE.  From a packet-switching perspective, the service provider's switch, to which a router might connect, is considered the DCE.

You want to connect two PCs together without

using a switch. Which type of cable will you use?

Crossover cable.

Which host is 10.2.78.1 /11 in?

11 bits is 255.224.0.0 and increments of 32 so

that host is in subnet 10.0.0.0.

Which of the below hosts are usable if the mask

is 255.255.255.240

192.168.1.16 - no, this is the subnet

192.168.1.30 - OK

192.168.1.31 - no, this is the broadcast

192.168.2.48 - no, this is the subnet

192.168.3.15 - no, this is the broadcast

What are the two ways to configure a NAT pool?

ip nat pool internet_out 10.0.0.1 10.0.0.10 prefix-length 24

ip nat pool internet_out 10.0.0.1 10.0.0.10 netmask 255.255.255.0

Which command will give you a summary of your

interfaces, IP addresses and if they are up or down?

show ip interface brief

You want to change your WAN interface from HDLC to PPP. Which command will accomplish this?

Router(config-if)#encapsulation ppp

You configure a new VLAN on your network and ping it to see if it is working. You get the below output:

Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:

.!!!!

Why did the first ping fail?

There was an ARP lookup to map the IP address to MAC address first.

What are the two names for the same CLI mode in a router or switch that, when accessed, enables you to issue EXEC commands that could be disruptive to router operations?

Enable mode and privileged mode. Both names are commonly used and are found in Cisco documentation.

What are three methods of logging on to a router or switch?

Console, auxiliary port, and Telnet. All three cause the user to enter user EXEC mode.

What is the name of the user interface mode of operation in which you cannot issue disruptive commands?

User EXEC mode.

What command do you use to receive command help if you know that a

show c?

. Help would appear immediately after you typed the ? symbol. You would not need to press Enter after the ?. If you did so, the router or switch would try to execute the command with only the parameters that you had typed after the ?.

While you are logged in to a router or switch, you issue the command

copy ? and get a response of “Unknown command, computer name, or host.” Offer an explanation for why this error message appears.

You were in user mode. You must be in enable/privileged mode to use the

copy command. When in user mode, the router does not provide help for privileged commands, and it treats the request for help as if there is no such command.

Is the number of retrievable commands based on the number of characters in each command, or is it simply a number of commands, regardless of their size?

The number of commands. The length (that is, the number of characters) of each command does not affect the command history buffer.

How can you retrieve a previously used command? (Name two ways.)

Ctrl-p and up arrow (literally the up arrow key on the keyboard). Not all terminal emulators support Ctrl-p or the up arrow, so recalling both methods is useful.

(another way is the show history command.)

After typing

show ip route, which is the only command that you typed since logging in to the router, you now want to issue the show ip arp command. What steps would you take to execute this command by using command-recall keystrokes?

Press the up arrow, press Backspace five times, and type

arp. The up arrow key retrieves the show ip route command. Backspace moves the cursor backward and erases the character. Typing inserts the characters into the line.

What configuration command causes the router or switch to require a password from a user at the console? What configuration mode context must you be in? (That is, what command[s] must be typed before this command after entering configuration mode?) List the commands in the order in which they must be typed while in config mode.

The line console 0 command is a context-setting command; it adds no information to the configuration. The command can be typed from any part of configuration mode. The login command, which follows the line console 0 command, tells Cisco IOS that a password prompt is desired at the console.

What configuration command is used to tell the router or switch the password that is required at the console? What configuration mode context must you be in? (That is, what command[s] must you type before this command after entering configuration mode?) List the commands in the order in which they must be typed while in config mode.

The

password command tells Cisco IOS the value that should be typed when a user wants access from the console. This value is requested by Cisco IOS because of the login command. The password xxxxxxx command must be typed while in console configuration mode, which is reached by typing line console 0.

When both encrypted and unencrypted enable passwords are configured, which one is used?

The enable secret (encrypted) password is used and the enable (unencrypted password) is ignored.

On a IP host, the IP address of some router to which the host sends packets when the packet's destination address in on a subet other than the local subnet.

The mask used in a Class A, B, or C network that does not create any subnets; specifically, mask 255.0.0.0 for Class A networks, 255.255.0.0 for Class B networks, and 255.255.255.0 for Class C networks.

On a router, the route that is considered to match all packets that are not otherwise matched by some more specific route.

The legal term for the demarcation or separation point between the telco's equipment and the customer's equipment.

A type of attack whose goal is to cause problems by preventing legitimate users from being able to access services, thereby preventing the normal operation of computers and networks.

Dynamic Host Configuration Protocol.  A protocol used by hosts to dynamically discover and lease an IP address, and learn the correct subnet mask, default geteway, and DNS server IP addresses.

A method of encoding data for transmission over a wireless LAN in which device uses 1 of 11 (in the USA) nearby frequencies in the 2.4-GHz range.

You want to clear the outputs on your serial interface showing errors on the interface. Which command do you type?

Router#clear counters serial 0

Which command will show you if you have a DTE or DCE cable connected to an interface?

Router#show controllers serial 0 (or whichever interface you have).

You want to see the NAT translations displayed on your screen as they happen for troublehooting purposes. Which command do you enter?

Router#debug ip nat

You want to log router informational messages to the routers buffer. Which command will do this?

Router#logging buffered

You want logging messages to show but not while you are entering configuration commands on the router. Which command will achieve this for you?

RouterA(config)#line console 0

RouterA(config-line)#logging synchronous

Which command on a router configures a DNS server for name lookups?

RouterA(config)#ip name-server 192.168.1.1

You want to monitor SNMP traffic on your router.

Which command will accomplish this?

debug snmp