CCNA基础知识题(英文版）

来源：vlan9.com 作者：出处：巧巧读书 2007-12-12 进入讨论组

301 Repeaters work at which layer of the OSI model?

A.) Network B.)
Session C.)
Transport D.)
Physical

Ans D Repeaters work at the Physical layer of the OSI model by regenerating the signal to
extend the distance it can travel.

302 What protocols can you use while testing Trace?

A.) DECnet B.) CLNS C.) IP D.) Old Vines E.) Vines F.) Chaos

Ans B C D E Type Trace ? At the router command prompt to see a list of available
supported protocols for tracing routes to IP addresses or Name addresses.

303 What utility can you use to see the path a packet takes through an internetwork?

A.) Route B.) SNMP C.) Trace D.) Ping

Ans C Trace - Uses Time-To-Live (TTL) values to generate messages from each router
used along the path. This is very powerful in its ability to locate failures in the path from the
source to the destination.

304 What is true about frame-relay DLCI?

A.) DLCI represents a single physical circuit B.) DLCI is optional in all frame-relay
networks C.) DLCI identifies a logical connection between DTE devices D.) DLCI is used
to tag the beginning of a frame with VLAN information

Ans C Data Link Connection Identifier (DLCI). A frame-relay service provider typically
assigns DLCI values that are used by frame-relay to distinguish between different virtual
circuits on the network. For the IP devices at each end of a virtual circuit to
communicate, their IP addresses are mapped to Dlci. Every DLCI value can have a global
or local meaning.

305 Which frame has a Type field to identify the upper-layer protocol?

A.) 802.3 B.) 802.2 C.) 802.5 D.) Ethernet_II

Ans D Ethernet_II has a Type field to identify the upper-layer protocol. This is best seen
by capturing packets with a sniffer and examining the packet.

306 Which protocol will let neighbor routers know if your internetwork
experienced congestion on a serial port?

A.) BootP B.) IP C.) ICMP D.) ARP E.) FTP F.) RARP

Ans C Internet Control Message Protocol - ICMP is a management protocol and messaging
service provider for IP. Its messages are carried as IP datagrams.

ICMP is used in the following events: Destination Unreachable - If a router cannot send an
IP packet any further, it uses an ICMP echo to send a message back to the sender notifying
it that the remote node is unreachable.

Buffer Full - If a routers memory buffer is full ICMP will send out a message to the
originator.

Hops - Each IP datagram is assigned a path. This consists of hops. If it goes through the
maximum number of hops, the packet is discarded and the discarding router sends an ICMP

echo to the host.

Ping - Ping use ICMP echo message to check connectivity.

307 What do you use the Aux port for?

A.) Console B.) Terminal editing C.) Modem D.) Backup logging

Ans C
The auxiliary port is used to connect a modem to for dial backups.

308 The CSMA/CD Ethernet IEEE committee is defines as which of the
following?

A.) 802.2 B.)

802.3 C.) 802.4
D.) 802.5
Ans B
The IEEE standard for Carrier Sense Multiple Access / Collision Detection is 802.3.
Also know as Ethernet.

309 How many Frame-relay encapsulation types are available with Cisco routers?

A.) Four B.)
Two C.) Five
D.) Three

Ans B
The two types of Frame relay encapsulation are Cisco and IETF.

310 What is the maximum hop count for Link-State protocols?

A.) 15 B.) there is no hop count limit C.) 256 D.) 16

Ans B Link-state-based routing algorithms – also known as shortest path first (SPF)
algorithms, maintain a complex database of topology information. Whereas the distance
vector algorithm has non-specific information about distant networks and no knowledge of
distant routers, a link-state routing algorithm maintains full knowledge of distant routers
and how they interconnect.

311 What information can you get from CDP info: (choose all that apply)

A.) Hardware platform B.) One address per protocol C.) Software platformD.) HostnameE.)
The same info as show version F.) Incoming/outgoing port

Ans A B D E F
All of the above except the software platform can be seen with the CDP information.

312 How does the cut-through switching technique work?

A.) By using broadcast address as source addresses B.) The switch waits only for the header
to be received before it checks the destination address and starts forwarding the packets C.)
The LAN switch copies the entire frame into its onboard buffers and then looks up the
destination address in its forwarding, or switching, table and determines the outgoing
interface D.) By using a Class I repeater in a collision domain

Ans B Cut-Through switching copies only the destination address which is the first 6 bytes
after the frame preamble into its buffer. The LAN switch then looks up the destination
address in its switching table and determines the outgoing interface. The frame is then
sent to the interface. A cut-through switch provides reduced latency because it begins to
forward the frame as soon as it read the destination address and determines the outgoing
interface.

313 What is the protocol number for TCP?

A.) 80 B.) 21
C.) 11 D.) 6

Ans D Transmission Control Protocol - TCP is a connection oriented transport layer
protocol with built in reliability. It takes a large block of data and breaks it down into
segments. It numbers and sequences each segment so the destination's TCP protocol can
re-assemble it back into the original order. TCP uses acknowledgements via sliding
windows. It has a large overhead due to built in error checking. The protocol use
protocol # 6.

314 Which of the following are Presentation Layer standards?

A.) JPEG and PICT B.) MPEG and MIDI C.) ASCII and EBCDIC D.) NFS and SQL

Ans A B C For example, the Presentation layer would be responsible for converting from
EDCDIC to ASCII. Data compression, decompression, encryption, and decryption are
presentation layer. Presentation layer standards include MPEG, MIDI, PICT, TIFF, JPEG,
ASCII, and EBCDIC.

315 What is the administrative distance for RIP?

A.) 100 B.)
90 C.) 120
D.) 110

The correct answer(s): C Routing Information Protocol (RIP) is a distance vector routing
protocol that uses hop count as its metric. The maximum hop count is 15, 16 hops is
considered unreachable. RIP updates are broadcast every 30 seconds by default. RIP has
an administrative distance of 120.

316 IP standard access lists use which of the following as a basis for permitting or
denying packets?

A.) destination address B.) port C.) protocol D.) source address

Ans D For Standard access lists, only the source address is used as a basis for permitting or
denying packets.

317 If a frame is received at a switch and only the destination hardware address is
read before the frame is forwarded, what type of switching method is this?

A.) Store-and-drop B.)
Latency
C.) Store-and-forward D.)
Cut-through

Ans D Cut-Through switching copies only the destination address which is the first 6 bytes
after the frame preamble into its buffer. The LAN switch then looks up the destination
address in its switching table and determines the outgoing interface. The frame is then
sent to the interface. A cut-through switch provides reduced latency because it begins to
forward the frame as soon as it read the destination address and determines the outgoing
interface.

318 What is the purpose and default value of the CDP timer command?

A.) 90 seconds; interval before an entry expires B.) 60 seconds; interval between updates C.)
60 seconds; interval before an entry expires D.) 90 seconds; interval between updates

Ans B The CDP timer controls when the update of CDP information should be sent to the
neighbor router.

319 Choose the following that are benefits to segmenting with router:

A.) Flow Control B.) Manageability C.) Multiple Active Paths D.) Explicit packet lifetime
control

Ans A B C D
All of the above are benefits of segmenting with a router.

320 When discussing static routes, what is the gateway parameter used for?

A.) Determining the dynamic route B.) Defining the subnet C.) Defining the Administrative
Distance D.) Determining the next hop

Ans D
The gateway parameter determines the path to the next router.

321 Which layer hides details of network dependent information from the higher
layers by providing transparent data transfer?

A.) Transport B.)
Physical C.) Data
Link D.) Session E.)
Application F.)

Network Ans A The
Transport layer does
the following:
Responsible for
end-to-end integrity
of data transmission.
Handles multiplexing
upper-layer
application, session
establishment and tear
down of virtual
circuits. Hides details
of network dependent
info from the higher
layers by providing
transparent data
transfer. The
'windows' works at
this level to control
how much
information is
transferred before an
acknowledgement is
required.

322 What information is provided by the local management interface (LMI)?

A.) LMI encapsulation type B.) The current DLCI values C.) The status of virtual circuits
D.) The global or local significance of the DLCI values

Ans B C D
LMI is a standard related to Frame Relay. It provides information related to PVCs.

323 Which layer defines the physical topology?

A.) Application B.)
Transport C.)
Network D.) Data
Link E.) Physical F.)
Session

Ans E The Physical layer deals with the actual physical medium and the method of
transporting 1s and 0s.

324 What key do you use to view the last command?

A.) Left Arrow B.)
Space Bar C.) Up
Arrow D.) Right
Arrow

Ans C
CTRL+P as well as the Up Arrow keyboard commands will show the last command.

325 Which of the follow do not belong to the customer?

A.) CO B.) DCE C.) Router D.) CPE E.) Demarc F.) DTE Ans A E Central Office (CO) - A
switching facility that provides the nearest point of presence for a provider's WAN service.

Demarcation (Demarc) - The point at which the CPE ends and the local loop portion of
the service begins. Usually the telecommunications closet at the subscriber's location.

CPE, DTE, DCE, and the router are all typically owned by the customer. DTE devices
are usually routers, DCE devices are CSUs/DSUs, or WAN interfaces that have a built in
CSU/DSU in the router. CPE stands for Customer Premise Equipment.

326 What is the IEEE specification for Spanning Tree Protocol?

A.) 802.9 B.)
803.ud C.) 803
D.) 802.1d

Ans D IEEE 8021.d Spanning Tree Protocol (STP) was developed to prevent routing loops
in a network. If a router, switch, or hub has more then one path to the same destination, a
routing problem could occur. To prevent this, the Spanning Tree Protocol is executed
between the devices to detect and logically block redundant paths from the network. The
main function of the Spanning Tree Protocol is to allow redundant network paths without
suffering the effects of loops in the network.

The Spanning Tree Algorithm (STA) implemented by STP prevents loops by calculating
a stable Spanning Tree network topology. When creating fault tolerant internetworks, a
loop-free path must exist between all Ethernet nodes in the network. Spanning Tree
frames called Bridge Protocol Data Units (BPDUs) are sent and received by all switches
in the network at regular intervals.

327 CO is an acronym for which of the following?

A.) Central Office B.)
Capital Office C.) Central
Operator D.) Company
Office

Ans A Central Office (CO) - A switching facility that provides the nearest point of presence
for a provider's WAN service.

328 What is convergence time?

A.) The update time B.) The time it takes to reload a router C.) The time it takes for a
packet to reach its destination
D.) The time is takes for all routers update their tables after a change takes place

Ans D
Convergence is slower for Distant Vector routing and is faster for Link State routing.

329 Which of the following are Session Layer standards?

A.) ASCII and EBCDIC B.) MPEG and MIDI C.) NFS and SQL D.) JPEG and PICT

Ans C Session layer protocols include NFS, SQL, RPC, Appletalk Session Protocol (ASP),
XWindows, and NetBEUI.

330 What is the IP extended access list range?

A.) 1000-1099 B.) 100-199 C.) 1-99 D.) 101-200

Ans B
100-199 is the range for Extended IP access lists.

331 Define Poison Reverse?

A.) To prevent regular update messages from reinstating a route that has gone down B.)
Packets sent out that are not destined for a network go to the default network C.)
Information received on an interface cannot be sent back out the same interface D.) When a
network goes down, the router enters in its table the number 16 to signify destination
unreachable

Ans D By entering a 16 as the hop count, the other routers know that the destination is
unreachable.

332 What is the default interval for SAP updates?

A.) 60 seconds B.) 15
seconds C.) 30 seconds
D.) 120 seconds

Ans A By default, the SAP (Service Access Protocol) sends out updates every 60 seconds.
This value can be changed to alter the update interval. To decrease WAN traffic, the
update interval could be increased to every 5 minutes.

333What does a router do with a packet that it does not have a destination
network for?

A.) Sends it to the Serial port B.) Drops the packet C.) Sends it back out the same interface
it received it in D.) Forwards the packet to the next hop

Ans B When a router does not have a destination for a packet, it drops the packet into the
bit bucket.

334 What type of frame does CDP use to gather information about it's neighbors?

A.) TCP/IP B.) Novell-ether C.) Subnetwork Access Protocol (SNAP) D.) Ethernet_II

Ans C Cisco Discovery Protocol is a proprietary protocol to allow you to access

configuration information on other routers and switches with a single command. It uses
SNAP at the Data-Link Layer. By default CDP sends out a broadcast every 60 seconds and
it holds this information for 180 seconds. CDP is enabled by default.

335 Which protocol is used for booting diskless workstations?

A.) IP B.) ARP C.) RARP D.) TCP E.) SNMP

Ans C Reverse Address Resolution Protocol - RARP is ARP's counterpart, but it resolves
IP addresses to MAC addresses typically on diskless workstations.

336 Which layer is responsible for synchronizing sending and receiving applications?

A.) Presentation B.) Session C.) Transport D.) Application E.) Network Ans D The
Application layer performs the following: Synchronizing sending and receiving applications.
Program-to program communication. Identify and establish the availability of the intended
communication partner, and determine if sufficient resources exist for the communication.
Popular application protocols include WWW, SMTP, EDI, FTP, Telnet, and SNMP

337 Which protocol gets a hardware address from a known IP address?

A.) RARP B.) TCP C.) IP D.) BootP E.) ARP F.) ICMP

Ans E Address Resolution Protocol - ARP is responsible for resolving MAC addresses to IP
address. It stores these in its arp cache for later use. It does this to inform a lower layer of
the destination's MAC address.

338 Which layer defines bit synchronization?

A.) Application B.) Network C.) Transport D.) Physical E.) Session F.) Session

Ans D
The Physical layers deals with synchronizing the 1s and 0s on the wire.

339 Which is true regarding half duplex Ethernet operation?

A.) Half Duplex ethernet technology provides a transmit circuit connection wired directly to
the receiver circuit at the other end B.) Half duplex transmission between stations is
achieved by using point to multipoint Ethernet and Fast Ethernet C.) With Half Duplex
transmission logically circuits feed into a single cable creating a situation similar to a one
way bridge D.) Half Duplex transmission between stations is achieved using Point to Point
Ethernet & Fast Ethernet

Ans C Half-Duplex - Capability for data transmission in only one direction at a time
between sending station and a receiving station.

340 When would you use ISDN?

A.) To connect LANs using POTS B.) To support applications requiring voice, data, and
video C.) When you need a consistent and very high rate of data speed D.) To connect to
IBM mainframes

Ans B IDSN supports high speed voice, data and video and is a good choice for many small

businesses.

350 Which protocol will send a message to routers if a network outage or
congestion occurs?

A.) ARP B.)
TCP C.) IP D.)
ICMP

Ans D Internet Control Message Protocol - ICMP is a management protocol and messaging
service provider for IP. Its messages are carried as IP datagrams.

ICMP is used in the following events:

Destination Unreachable - If a router cannot send an IP packet any further, it uses an
ICMP echo to send a message back to the sender notifying it that the remote node is
unreachable.

Buffer Full - If a routers memory buffer is full ICMP will send out a message to the
originator.

Hops - Each IP datagram is assigned a path. This consists of hops. If it goes through the
maximum number of hops, the packet is discarded and the discarding router sends an ICMP
echo to the host.

Ping - Ping use ICMP echo message to check connectivity.

351 What are the 2 functions of the Data Link Mac layer?

A.) Handles access to shared media B.) Manages protocol access to the physical network
medium C.) Provides SAPs for higher level protocols D.) Allows multiple devices to
uniquely identify one another on the data link layer

Ans B D
These are the two primary functions of the MAC layer.

352 Which layer is responsible for coordinating communication between systems?

A.) Application B.) Network C.) Session D.) Transport E.) Physical F.) Data Link

Ans C The Session layer performs the following: Responsible for establishing and
maintaining communications channels. In practice, this layer is often combined with the
Transport Layer. Dialog control between devices or nodes. Organizes the communication
through simplex, half and full duplex modes. Deals with connection establishment, data
transfer, and connection release.

353 What is the default CDP broadcast update rate for Cisco routers?

A.) 120 seconds B.)
60 seconds C.) 30
seconds D.) 90
seconds

Ans B Cisco Discovery Protocol is a proprietary protocol to allow you to access
configuration information on other routers and switches with a single command. It uses
SNAP at the Data-Link Layer. By default CDP sends out a broadcast every 60 seconds and
it holds this information for 180 seconds. CDP is enabled by default.

354 You need to come up with a TCP/IP addressing scheme for your company. How
many network IDs must you allow for when you define the subnet mask for the
network?

A.) One for each WAN link B.) One for each router interface C.) One for each NIC
installed in each client D.) One for each subnet with hosts E.) One for each host ID

Ans A D When determining Network Ids, you need to take into account each Subnet and
Each WAN link you will have. Add these numbers up and you will find the answer to
which Network ID you can use.

355 What is the protocol number for UDP?

A.) 6 B.) 17
C.) 25 D.)
21

Ans B User Datagram Protocol - UDP is a connectionless oriented transport protocol for
use when the upper layers provide error-recovery and reliability. UDP does not sequence
data or re-assemble it into any order after transmission. This protocol uses Port 17.

356 What is the default LMI type?

A.) Cisco B.)
ANSI C.) IETF
D.) Q933a

Ans A Local Management Interface (LMI) was developed in 1990. LMI messages
provide information about the current DLCI values, the global or local significance of the
DLCI value, and the status of virtual circuits.

There are three types of LMI standards: ANSI - Annex D defined by ANSI standard
T1.617 ITU-T (Q.933A) - Annex A defined by Q933A Cisco (default) - LMI defined by the
gang of four

357 You have two Cisco routers setup back-to-back in a lab using DTE/DCE cables.
To which router would you add the clockrate command?

A.) The serial port on the DCE router B.) The
Ethernet port on the DTE router C.) The
Ethernet port on the DCE router D.) The serial
port on the DTE router

Ans A In order to connect routers back-to-back, a clock rate must be set on the router with
the DCE cable. This will provide the clocking usually performed by a DSU/CSU. It is
recommended that a bandwidth statement be added to the interface because some routing
protocols, such as IGRP, use this to make routing decisions.

358 How does a switch use store and forward?

A.) By using a Class I repeater in a collision domain

B.) The LAN switch copies the entire frame into its onboard buffers and then looks up the
destination address in its forwarding, or switching, table and determines the outgoing
interface C.) By using broadcast addresses as source addresses D.) The switch waits only
for the header to be received before it checks the destination address and starts forwarding
the packets

Ans B

Store-and-Forward switching copies the entire frame into its buffer and computes the CRC.
If a CRC error is detected, the frame is discarded, or if the frame is a runt (less than 64
bytes including the CRC) or a giant (more than 1518 bytes including the CRC). The LAN
switch then looks up the destination address in its switching table and determines the
outgoing interface. The frame is then forwarded to the outgoing interface. Cisco Catalyst
5000 switches uses the Store-and-Forward method. The problem with Store-and-Forward
switching is latency is increased. Latency also varies with the size of the frame. The
larger the frame, the more latency associated. This of course is due to the fact that the
entire frame is copied into its buffer before being forwarded.

359Which of the following are valid WAN terms?

A.) DTE B.) DCE C.) Demarc D.) CPE

Ans A B C D
All of the above are valid WAN terms.

360 Which two describe frame tagging?

A.) Examines particular info about each frame B.) A unique ID placed in the header of each
frame as it traverses the switch fabric C.) A user- assigned ID defined to each frame D.)
The building of filter tables

Ans B C Frame identification (frame tagging) uniquely assigns a user-defined ID to each
frame. This technique was chosen by the IEEE standards group because of its scalability.

In this approach, a unique user-defined identifier is placed in the header of each frame as
it's forwarded throughout the switch fabric. The identifier is understood and examined by
each switch prior to any broadcasts or transmissions to switch ports of other switches,
router, or end-station devices. When the frame exits the switch fabric, the switch
removes the identifier before the frame is transmitted to the target end-station.

The following points summarize frame tagging:
Used by Catalyst 3000 and 5000 series switches

Specifically developed for multi-VLAN, inter-switch communication Places a unique
identifier in the header of each frame Functions at layer 2 Requires little processing or
administrative overhead

361 A ISDN BRI circuit can be described as a which of the following?

A.) 3B channels B.) 2-64Kbps B channels and 1-16Kbps D channel C.) none of the above
D.) 2-64Kbps B channels and 1-16Kbps C channel

Ans B There are two types of ISDN Channels : BRI (Basic Rate Interface) - is 2 64Kbps B
channels for data and one 16Kbps D channel for link management. PRI (Primary Rate
Interface) - is 23Kbps B channels and 1 64Kbps D channel.

362 The two sublayers of the IEEE Data Link Layer are which of the following?

A.) Link and Logical Control B.) Data Link and LLC C.) Logical Link Control and Media
Access Control D.) Data Link and MAC

Ans C Logical Link Control Sublayer - Acts as a managing buffer between the upper layers
and the lower layers. Uses Source Service Access Points (SSAPs) and Destination Service
Access Points (DSAPs) to help the lower layers talk to the Network Layer.

Media Access Control (MAC) -The MAC sublayer manages protocol access to the
physical network medium. The IEEE MAC specification defines MAC addresses, which
allow multiple devices to uniquely identify one another at the data link layer.

363 The --terminal no editing -- command will perform what function?

A.) Edit the contents of NVRAM B.) Allows access to the terminal port C.) Stops the
advanced editing feature D.) Enable password functions

Ans C The command to disable advanced editing feature is: Router(config)# terminal no
editing

364 Which two of the following are valid ways to have multiple encapsulation types
on a single interface?

A.) This is not possible B.) subinterfaces C.) additional physical interfaces D.) secondary
addresses

Ans B D Cisco routers do not allow multiple encapsulation types on a single interface.
Therefore, it is necessary to create either a Secondary Network, or a Subinterface and
assign a new encapsulation type.

365 Which 3 statements describe default encapsulation and LMI type
configuration?

A.) There are only four encapsulations and 3 LMI type options B.) The LMI type config
term options C.) In release 11.3 the LMI type is autosensed D.) The default LMI is Cisco E.)
IETF encap must be configured unless the connecting routers are both cisco

Ans C D E The above 3 statements best describe default encapsulation and LMI type
configuration for Cisco routers.

366 Which can be true regarding VLANs?

A.) They are created by location B.) They
are created by function C.) They are
created by department D.) They are

created by group

Ans A B C D A Virtual LAN (VLAN) is a switched network that is logically segmented by
communities of interest without regard to the physical location of the users. Each port on
the switch can belong to a VLAN. Ports in a VLAN share broadcasts. A VLAN looks like,
and is treated like, it's own subnet. The benefits of VLANs are as follows: Simplify moves,
adds, and changes Reduce administrative costs Have better control of broadcasts Tighten
network security Microsegment with scalability Distribute traffic load Relocate server into
secured locations

367 What is true when using DDR?

A.) HDLC is the preferred encapsulation B.) You must use static routing C.) You should
use dynamic routing D.) You should use ISDN

Ans B When using Dial Demand Routing (DDR), static routes must be specified in order to
route packets.

368 If you are running Token Ring with Novell IPX routing, which encapsulation
should you use?

A.) SAP B.)
SNAP C.) 802.5
D.) 802.2

Ans B
Token Ring with Novell IPX routing uses the SNAP protocol, not 802.5.

369 What are the 3 ways routers learn paths to destination networks?

A.) Dynamic B.) Static C.) Routing tables D.) Default

Ans A B D There are three methods in which routers can learn paths to destination
networks, they are: 1) Static - The administrator manually enters the routes. 2) Dynamic - A
routing protocol is used. 3) Default - A gateway of last resort is set.

370 Bridges work at what layer of the OSI model?

A.) Data Link B.)
Network C.) Physical D.)
Application

Ans A Bridges work at Layer 2 (Data Link) because they examine the MAC address of the
packet which they base decisions upon.

371 What is the default switching method for the Cisco 5000 series?

A.) Cut-through B.) Store-and-splice C.) Latency D.) Store-and-forward

Ans D Store-and-Forward switching copies the entire frame into its buffer and computes the
CRC. If a CRC error is detected, the frame is discarded, or if the frame is a runt (less than
64 bytes including the CRC) or a giant (more than 1518 bytes including the CRC). The
LAN switch then looks up the destination address in its switching table and determines the

outgoing interface. The frame is then forwarded to the outgoing interface. Cisco Catalyst
5000 switches uses the Store-and-Forward method. The problem with Store-and-Forward
switching is latency is increased. Latency also varies with the size of the frame. The
larger the frame, the more latency associated. This of course is due to the fact that the
entire frame is copied into its buffer before being forwarded.

372 The benefits to segmenting with Bridges are which of the following?

A.) Scalability B.) Datagram filtering C.) Manageability D.) Reliability

Ans A C D
Manageability, reliability and scalability are all benefits to segmenting with bridges.

373 What is the administrative distance for IGRP?

A.) 90 B.)
120 C.) 110
D.) 100

Ans D IGRP is a distance vector routing protocol designed by Cisco. The maximum hop
count is 255, and it uses a combination of variables to determine a composite metric.
IGRP has an administrative distance of 100.

374 On an ISDN BRI interface, the control channel is the 'D' channel. What is the
rate of this channel?

A.) 64 Kbps B.) 1.544
Mbps C.) 128 Kbps D.)

2.048 Mbps E.) 16 Kbps
Ans E
16K for the D channel (control)
64K for the two B channels (data)

375 MIDI and MPEG are examples of what layer of the OSI seven layer model?

A.) Session B.) Network C.) Datalink D.) Transport E.) Application F.) Presentation

Ans FThe OSI Presentation layer includes EBCIDIC, ASCII, PICT, GIF, MIDI, and MPEG.
Encryption can also occur at this layer.

376 Which ISDN specification series deals with Concepts and Terminology?

A.) World Series B.) I- SeriesC.) Q-Series D.) 911-Series E.) J-Series F.) F-Series

Ans B

The 2 most important ISDN specifications are Q & I: Q - Call setup and teardown. I -
Concepts and terminology.

377 Which of the following is an example of the Physical Layer?

A.) SQL B.) IP C.) LLC D.) DDP E.) Ethernet

Ans E
FDDI, Token Ring and Ethernet are all physical layer framing standards.

378 In regards to the ISDN BRI standard, which channel is used for control?

A.) B B.) D C.)
E D.) I E.) Q

Ans B
B is Bearer for Data (2 channels at 64kb each).
D is for Control (16kb).

379 Which protocol resolves an IP address to a MAC address?

A.) DHCP B.)
RARP C.) ARP
D.) NBP E.) DNS

Ans C The Address Resolution Protocol (ARP) sends out a broadcast to determine the
MAC address from the IP address.

380 Which of the following is an example of the Network Layer?

A.) TCP B.) IP C.) SQL D.) Token Ring E.) LLC

Ans B Most protocol suites have different OSI layer protocols within them. At layer 3, IP
is for TCP/IP. TCP is layer 4. IPX is for IPX/SPX. SPX is layer 4. DDP is for Appletalk

381 The Internet Control Message Protocol occurs at what layer of the seven layer
model?

A.) Physical B.) Transport C.) Session D.) Datalink E.) Presentation F.) Network

Ans F ICMP is used for error handling and testing at layer 3. Ping and traceroute are
examples of ICMP.

382 Which of the following are examples of the Session Layer?

A.) IP B.) Netbios Names C.) NFS D.) Token Ring E.) SQL F.) TCP

Ans B C E
Session layer examples include Netbios Names, SQL, NFS, X Windows, and RPC.

383 What is the regional telco office called, where the customers local loop
terminates?

A.) Demarc B.) DTE C.) DCE D.) CO E.) CPE

Ans D
The Central Office (CO) is the Telephone Company (Telco) location nearest you.

384 What is the default LMI type for Cisco Routers that are using Frame-Relay?

A.) Gandalf5 B.) Q933A C.) Cisco D.) IETF E.) ARPA F.) SAP

Ans C
Local Management Interface (LMI) types are Cisco, ANSI, and Q933A.

385 Most routing protocols recognize that it is never useful to send information about
a route back out the direction from which the original packet came. This is an
example of which routing technology?

A.) Split Horizon B.) LMI C.) Triggered Updates D.) Poison Reverse E.) SYN, ACK F.)
DLCI

Ans A The golden rule of Split Horizon: Do not send any update packet back out the same
interface that it was received or learned from. Poison Reverse is typically used on larger
networks, where a more aggressive routing loop solution is required.

386 Which layer of the 7 layer model is responsible for representing the application
information between 2 different OS's? For example, converting ASCII to EBCIDIC.

A.) Transport B.) Application C.) Physical D.) Session E.) Presentation F.) Network

Ans E
The OSI Presentation layer formats the data, which includes encryption services.

387 Which type of switching reads in the entire frame before forwarding it?

A.) TablingB.) Store-and-Forward C.) Inverse ARP D.) Fast Forward E.) Cut-Through F.)
Routing

Ans B Store-and-Forward is slower, but it checks the frame for errors before forwarding.
This can actually help to improve overall network performance on noisy lines.

388 Which OSI Reference Layer is concerned with path determination?

A.) Datalink B.)
Physical C.) Network D.)
Transport E.) Session

Ans C
The Network layer is where routing occurs.

389 Which of the following are examples of the Datalink Layer?

A.) LLC B.) SQL C.) TCP D.) Token Ring E.) IP

Ans A

MAC and LLC are the sublayers of the Datalink layer.

390 What is the standard ISDN term for a non-native analog telephone?

A.) TE1 B.) TA C.)
LE D.) TE2 E.) ET

Ans D Terminal Equipment 2 (TE2) does not support native digital ISDN. The analog
device will require an external analog to digital converter.

391 Which Distance Vector characteristic can help to speed up convergence?

A.) Triggered Updates. B.) Split Horizon. C.) Poison Reverse. D.) Hold Down timers. E.)
Inverse ARP.

Ans A Instead of waiting on a pre-set periodic interval (before sending the routing table),
DV routing protocols can send triggered updates to immediately notify the neighbor routers.
Hold down timers, Poison Reverse, and Split Horizon are features that are used to avoid
routing loops.

392 Which type of switching is considered to be 'wire speed?'

A.) Cut-Through B.) Multiplexed C.) Inverted D.) Layer 4 E.) Store and Forward F.) Layer
3

Ans A Cut-Through is the fastest mode of switching. Store and Forward reads in the
entire frame, confirms the frame is valid, and then forwards the frame onto the wire.
Cut-Through only checks the destination header in the frame and immediately forwards the
frame onto the wire, without checking the frame to be valid. Layer-3 switching is actually
routing.

393 The Datalink layer works with which of the following:

A.) Packets B.) Bits C.) Globules D.) Frames E.) Segments

Ans D Physical - bits Datalink - frames Network - packets

394 What is a characteristic of Store and Forward switches?

A.) They forward the frame before it is completely read. B.) They work at wire speed. C.)
They are the same a Cut-Through switching. D.) They read the entire frame and check CRC
before forwarding. E.) They decrease latency.

Ans D
Store and Forward switch will not forward fragments.

The longer the frame, the longer the delay (latency) before the switch can forward.

395 Station A is transmitting data to station B, and expects an acknowledgment after
every 400 bytes. After transmitting data for a while, the two stations determine the

line is reliable and change to expecting and acknowledgement every 600 bytes. This is
an example of (pick the best answer only):

A.) BECN B.) Sliding Windows C.) Poison Reverse D.) Countdown timers E.) Split
Horizon F.) Count to infinity

Ans B A TCP/IP 'window' is the amount of data (number of bytes) that the sending station
will transmit before expecting an acknowledgement back. If the stations can change that
window size on the fly, that is called a sliding window. This is done to optimize
performance.

396 Which device listed below provides clocking for the line?

A.) DCE B.) CPE C.) CO D.) DTE E.) Demarc

Ans A The Data Circuit-terminating Equipment (DCE) is responsible for providing the
clocking on the wire. HINT: When You see the 'C' in 'DCE', think 'Clocking' t.

397 Which OSI Reference Layer controls application to application communication?

A.) Datalink B.) Network C.)
Transport D.) Session E.)
Physical

Ans D The Session layer controls a conversation between applications. The Transport layer
controls communications between hosts.

398 The Datalink Layer is broken down into 2 layers, LLC and MAC. The LLC
establishes media independence and what else?

A.) Provides Windowing. B.) Provides flow control. C.) Provides SAP's (Service Access
Points). D.) The Datalink layer does not have sublayers. E.) Provides SAP's (Service
Advertising Protocol). F.) RIP Updates.

Ans B C OSI layer-2 SAP allows the upper layers to encapsulate multiple layer 3
protocols. IPX SAP is a protocol used to advertise NetWare services every 60 seconds.

399 When a Distance Vector routing protocol detects that a connected network has
gone down, it sends out a special routing update packet, telling all directly connected
routers that the distance to the dead network is infinity. This is an example of which
routing technology?

A.) ICMP. B.) Only Link State routing protocols have this intelligence.C.) Triggered
updates. D.) Garrison-4. E.) Split Horizon. F.) Poison Reverse.

Ans F Instead of just removing the route from the routing update, Poison Reverse sets the
distance to 'infinity' (for IP RIP this is a hop count of 16). This immediately makes the
route invalid for all neighboring routers.

400 Which of the following would be displayed by the command 'SHOW CDP
NEIGHBOR DETAIL'?

A.) The incoming/outgoing port. B.) The hardware platform. C.) One address per protocol.
D.) Amount of Flash Memory Available E.) The routers hostname. F.) The subnet mask, if

IP is configured.

Ans A B C E CDP shows a lot of the same info that 'show version' does locally, but
FLASH memory is not part of it. The 'detail' keyword is optional, but even when used,
IP subnet mask information is not displayed by CDP for IP interfaces.