CCNA 真题: TCP/IP

CCNA 2·练习题及答案82007-11-26 09:001 How does a source host use ICMP to confirm that a destination host is reachable?

The source host sends an ICMP echo request to the destination router which responds with an ICMP echo reply confirming the reachability of the destination host.
The source host sends a data packet and receives an ICMP host unreachable packet from the destination host if the data packet cannot be delivered.
The source host sends an ICMP packet with a TTL value of 1 and receives an ICMP reply with a TTL value of 0 from the destination host.
(√)The source host sends an ICMP echo request and receives an ICMP echo reply from the destination host.



2 Which type of message is generated by a host when the ping command is entered?

(√)ICMP echo request
ICMP echo reply
UDP echo request
UDP error message



3 Which of the following start the test of destination reachability?

(√) echo request issued by source
echo reply issued by source
echo request issued by destination
echo reply issued by destination



4 Which two statements are true regarding ICMP? (Choose two.)

ICMP provides reliability for the TCP/IP protocol stack.
(√) ICMP is a component of the TCP/IP protocol stack.
(√) ICMP notifies the sender that data transmission errors have occurred.
ICMP is connection-oriented.
ICMP messages are propagated to all intermediate devices.



5 How does ICMP improve data transfer reliability in IP networks?

Each router in the path reads ICMP packets and uses the information to update routing tables.
ICMP can correct many network problems as they occur.
(√) ICMP error messages are returned to the sending device when a packet is dropped by a router.
ICMP packets report the intermediary devices that a packet passed through before failure occurred.



6 Which layer protocols provide reliability for IP when needed?

ICMP and ping
RIP and TTL
(√) upper layer protocols
lower layer protocols
Internet layer protocols
network access layer protocols



7 Which devices along a data transmission path are notified by ICMP when delivery failures occur?

(√) source devices only
destination devices only
intermediary devices
source and destination devices
source, intermediary, and destination devices



8 When a datagram is processed by a router on the path from source to destination, what happens to the value in the TTL field?"

It is increased by one.
(√)It is decreased by one.
It stays the same.
It is reset to 0.
Nothing.



9 Which condition could cause a fragmentation needed ICMP destination unreachable message to be sent?

A low bandwidth WAN link has become congested with IP traffic.
(√) A packet is forwarded from a Token Ring network to an Ethernet network.
A network is not reachable because of faulty routing information.
The address specified by the sending host is nonexistent.



10



Workstation 1 sent a data packet to Workstation 4. It never arrived because Fa0/0 interface went down on Router C. How will the devices handle this failure?

Workstation 4 will send an error message to Router C and Workstation 1 that it did not receive the packet.
(√) Router C will use ICMP to send a message back to Workstation 1 indicating that the packet could not be delivered.
Router C discards the packet without providing notification to any device.
Router C uses ICMP to correct the failure and transmits the data to Workstation 4.
Workstation 1 will use ICMP to correct the problem and then notify Router C to continue the transmission.



11 Which three conditions must be met in order for host to host communication over an internetwork to occur on IP networks? (Choose three.)

The routing protocols configured on the source and destination networks must be the same.
(√) A default gateway must be properly configured on the hosts and local networks.
(√) Intermediary devices, such as routers, must be present on the network and have knowledge of how to reach the destination network.
The source and destination host subnet masks must match.
(√) The IP addresses of the hosts must be in the same network or subnet as their respective gateway devices.

Module 1 Exam - CCNA 21 Why is a console connection to a router or switch preferred when troubleshooting? (Choose two.)

can be accessed remotely
(√)does not depend on network services
(√)displays startup and error messages by default
does not require special components



2 A router is composed of many internal components. Which of the following components stores a copy of the router's configuration file?

metal-oxide memory
read only memory
flash memory
(√)non-volatile random access memory



3 Which of the following layers of the OSI model are incorporated in WAN standards? (Choose two.)

(√)physical layer
application layer
transport layer
(√)data link layer
session layer



4 Which basic components do a router and a standard desktop PC have in common? (Choose three.)

(√)CPU
hard drive
(√)input/output interfaces
keyboard
monitor
(√)system bus



5 During the initial configuration of a 2600 series Cisco router, which cable is required for connecting a PC to the console port?

twisted
crossover
(√)rollover
straight



6

Terminal emulation software, such as HyperTerminal, can be used to configure a router. Which of the following HyperTerminal options shown in the graphic are correctly set to allow configuration of a Cisco router? (Choose three.)

bits per second
(√)data bits
(√)parity
(√)stop bits
flow control



7 Which of the following descriptions are true regarding the management connections on a Cisco router? (Choose three.)

They are non-network connections.
(√)They are used to connect the router to the rest of the production network.
They are synchronous serial ports.
(√)They are used for initial router configuration.
(√)They are asynchronous serial ports.
They are accessed using their assigned IP address.



8 What do routers use to select the best path for outgoing data packets?

ARP tables
bridging tables
(√)routing tables
switching tables



9 Several Ethernet hosts on a LAN need the gateway services of a Cisco 2500 series router. Which of the following would be needed to physically connect a router to all of the hosts on the LAN? (Choose two.)

a crossover cable between the transceiver on a router and a switch
crossover cables between a switch and hosts on a LAN
a straight-through cable between the auxiliary port on a router and a switch
(√)a rollover cable between the console port on a router and a switch
(√)straight-through cables between a switch and hosts on a LAN
a straight-through cable between the transceiver on a router and a switch



10 An internetwork must include which of the following? (Choose three.)

(√)switching
static addressing
IETF standardization
(√)dynamic or static routing
(√)consistent end-to-end addressing



11 Select the statements that correctly describe flash memory in a 2600 series router? (Choose two.)

holds the startup configuration by default
(√)can be upgraded with single in-line memory modules
(√)stores Cisco IOS software images
stores routing table information by default
maintains the only copy of an IOS image after the router is booted



12 Which of the following are functions of NVRAM? (Choose two.)

stores the routing table
(√)retains contents when power is removed
(√)stores the startup configuration file
contains the running configuration file
stores the ARP table



13 Which router component holds the configuration file when power is lost?

volatile random access memory
read only memory
(√)non-volatile random access memory
flash memory



14 Which of the following devices are used in the construction of a WAN? (Choose three.)

hubs
(√)routers
(√)communication servers
transceivers
(√)modems
multi-port repeaters



15 ABC Company just purchased three new routers to start their company network. Which items are needed to establish a terminal session between a PC and the router for the initial configuration? (Choose three.)

straight-through cable
(√)terminal emulation software
(√)rollover cable
(√)RJ-45 to DB-9 connector
V.35 cable


16 Which of the following are true regarding router interfaces? (Choose three.)

provide temporary memory for the router configuration files
(√)connect the router to the network for packet entry and exit
(√)can be on the motherboard or a separate module
hold the IOS image
(√)connect the router to LANs and WANs



17 The console port can be used for which of the following? (Choose three.)

(√)debugging
(√)password recovery
routing data between networks
(√)troubleshooting
connecting one router to another



18 Which of the following describes the function of a WAN?

connects peripherals in a single location
connects multiple networks in a single building
provides connectivity on a LAN
(√)provides connectivity over a large geographic area



19 Which of the following are functions of RAM? (Choose three.)

contains startup configuration file
(√)stores routing table
(√)holds fast switching cache
retains contents when power is removed
(√)stores running configuration file



20 What contains the instructions that a router uses to control the flow of traffic through its interfaces?

packet configuration
configuration files
(√)flash memory
internal components



21 Which of the following tasks can be accomplished through a management connection on a router? (Choose three.)

(√)troubleshooting problems
(√)monitoring the system
capturing LAN data packets
(√)configuring the router
routing data packets