思科认证考试（ＣＣＮＡ）考试模拟题６０—７１及答案(2)
添加时间: 2007-9-8 3:10:24 作者: Cisco认证考试 阅读次数:49 来源: http://www.d9soft.com
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 104
CCNA试题60-71答案
60. [RINx] What condition does Serial 0 down & protocol up represent?
a) The interface is disconnected but keep alives are being received
b) The interface is working properly but keep alives are not being received
c) The interface is bad and should be replaced
d) The interface is working correctly.
e) Condition not possible
Answer
e) Condition not possible
The down and up combination is not legal
Let’s review all the possibilities:
Serial 0 down & line protocol down
Serial 0 administratively down and line protocol down
Serial 0 up and protocol down
Serial 0 up and protocol down (looped)
Serial 0 up and protocol up
Serial 0 up and protocol up - is a fully working link which means that both the interface and the line protocol have successfully initialized and protocol keep alives are being received.
Serial 0 administratively down - and line protocol down this condition indicates that a shut command has been configured on this interface, to reverse this condition execute a no shut command
Serial 0 up and protocol down (looped) - this condition indicates that this interface is receiving it’s own keep alives which is a result of putting a CSU/DSU in loopback mode.
Serial 0 down & line protocol - down this means that carrier detect signal (DCD) is not being received. You might want to make a call to your carrier to see if the local loop is up!!
Serial 0 up and protocol down - if a interface has detected a large number of errors during a keep alive period which could be caused by a defective CSU/DSU.
61.[CxNx] What command correctly displays the running configuration file?
a) show configuration
b) show running-configuration
c) show active-configuration file
d) write terminal
e) all of the above
Answer
b) show running-configuration
d) write terminal
Many times in class some students who have some experience with older versions are familiar with the show configuration command and do not realize that this command shows the start-up configuration.
Usually they have made a change to the running-configuration. Then they issue the show configuration command and they think something is wrong with the router because the change doesn’t show up.
Since version 10.3, the command show running-configuration will display the running configuration command. Prior to this version, write terminal was the appropriate command.
In general many of the 10.3 and later commands are intuitive such as:
show run
show start
copy run start
copy start run
What may not be intuitive is that when a copy is made to the running-configuration this is not the same as a DOS type copy - in other words the original running configuration is not lost. The resulting running configuration file is a blending of the two files.
62. [RINx] What is the purpose of TTL?
a) Prevent routing loops
b) Prevents Timely Telnet Losses
c) Remind engineers that life is short
d) To prevent IP datagrams from living long and fruitful lives
e) To prevent IP datagrams that are caught in a routing loop from traversing the network forever.
Answer
e) To prevent IP datagrams that are caught in a routing loop from traversing the network forever.
Time To Live is how long a packet can survive on the network before it will be removed. Each host on the net should decrement the time TTL by one.
Usually 255 on an ethernet segment
The logan’s run effect!
63. [RINx] Which should be the subnet mask for a class C address if 62 hosts are required?
a) 255.255.255. 192
b) 255.255.192.0
c) 0.0.0.192
d) 255.255.255.62
e) none of the above
Answer
a) 255.255.255.192
To calculate the number of host or networks using the formula 2 to the nth degree - 2 where the nth degree is the number of bits that will be used to describe the host or the network.
To answer this question we first have to determine how many host bits would we need to have at least 62 unique combinations.
Using our formula we need to have 6 host bits 2 to the 6th power - 2 = 62
This would leave us with 2 network bits therefore the mask is 192 in the fourth octet.
64. [CxNx] After the configuration command is used, when does it become effective?
a) immediately
b) after the router is rebooted
c) after you exit the configuration mode
d) depends on the change that is made
e) All of the above
Answer
a) immediately
There are times when the router needs to be bounced, but it is very rare.
65. [RxNx] Which one of the following is true concerning IPX load balancing?
a) Activated by default
b) Must be configured
c) IPX does not load balance
d) Requires a Novell File Server
e) None of the above
Answer
b) Must be configured
IPX load balances when configured, the command to use is ipx maximum-paths. So if you have equal cost paths to a destination, the default is the router will choose the first path it receives, unlike Cisco ’s implementation of IP RIP that will use up to 4 equal cost paths
66. [BxNx] What is the purpose of spanning tree?
a) Prevents bridging loops
b) Prevents routing loops
c) Cisco supported feature that can be used per VLAN
d) Can be initiated on any routed interface
e) All of the above
Answer
a) Prevents bridging loops
c) Cisco supported feature that can be used per VLAN
Transparent bridging requires that only one way exists through the bridge circuit to prevent routing loops. Also Cisco switching supports spanning tree an a per VLAN basis. This is done by placing selected ports in a blocking mode. Remember that a bridge either forwards a packet or filters a packet based on it’s mac address.
Questions 67 - 71 refer to the following diagram and information.
The above figure represents a frame-relay network with PVC’s configured for a hub and spoke design with corresponding DLCI numbers. Assume all connections are with the serial 0 interface. Please refer to the above figure for questions 67-71.
67. [FINx] Given the following configuration for Router A:
Router_a(config)#interface s0
Router_a(config-if)#encapsulation
frame-relay
Router_a(config-if)#frame-relay
lmi-type ansi
Router_a(config-if)#frame-relay map ip
172.16.1.2 100
Router_a(config-if)#frame-relay map ip
172.16.1.3 101
Router_a(config-if)#frame-relay map ip
172.16.1.4 102
Router_a(config-if)#frame-relay map ip
172.16.1.5 103
Router_a(config-if)#frame-relay map ip
172.16.1.6 104
Router_a(config-if)#ip address
172.16.1.1 255.255.255.0
Which of the following is the proper configuration
for Router F?
a)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
b)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
c)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 104
d)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 604
e)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.6 604
Answer
d)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 604
There are several configuration parameters that must be checked to answer these frame relay questions.
LMI
Does not have to match end to end this is communication between the local router and the local frame relay switch
Encapsulation
This parameter needs to match end to end.
Frame map statement
The ip address here needs to be the next hop address and the DLCI number needs to be the local DLCI.
The local DLCI for Router F is 604
The next hop address is Router A 172.16.1.1
Encapsulation is Cisco the default
68. [FINx] Given the following configuration for Router A:
Router_a(config)#interface s0
Router_a(config-if)#encapsulation
frame-relay ietf
Router_a(config-if)#frame-relay
map ip 172.16.1.2 100
Router_a(config-if)#frame-relay
map ip 172.16.1.3 101
Router_a(config-if)#frame-relay
map ip 172.16.1.4 102
Router_a(config-if)#frame-relay
map ip 172.16.1.5 103
Router_a(config-if)#frame-relay
map ip 172.16.1.6 104
Router_a(config-if)#ip address
172.16.1.1 255.255.255.0
Which of the following is the proper configuration for Router F?
a)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
b)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type ansi
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 104
c)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type cisco
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 104
d)
Router_f(config)#interface s0
Router_f(config-if)#encapsulation frame-relay
Router_f(config-if)#frame-relay lmi-type cisco
Router_f(config-if)#ip address
172.16.1.6 255.255.255.0
Router_f(config-if)#frame-relay
map ip 172.16.1.1 604
e) None of the above.
Answer
e) None of the above
There are several configuration parameters that must be checked to answer these frame relay questions.
LMI
Does not have to match end to end this is communication between the local router and the local frame relay switch
Encapsulation
This parameter needs to match end to end.
Frame map statement
The ip address here needs to be the next hop address and the DLCI number needs to be the local DLCI.
The local DLCI for Router F is 604
The next hop address is Router A 172.16.1.1
Encapsulation of Router A is IETF
Encapsulation of all our choices is Cisco
69. [FINx] Given the following configuration for Router A:
Router_a(config)#interface s0
Router_a(config-if)#encapsulation
frame-relay ietf
Router_a(config-if)#frame-relay lmi-type ansi
Router_a(config-if)#frame-relay
map ip 172.16.1.2 100
Router_a(config-if)#frame-relay
map ip 172.16.1.3 101
Router_a(config-if)#frame-relay
map ip 172.16.1.4 102
Router_a(config-if)#frame-relay
map ip 172.16.1.5 103
Router_a(config-if)#frame-relay
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