Cisco CCNA mock exam questions sample test – Question 89

.R1 and R2 are connected as shown in the diagram and are configured as shown in output in the partial output of the show run command.
The command ping R2 fails when executed from R1. What command(s) would allow R1 to ping R2 by name?

A. R1(config)#int S1
R1(config-if)#no ip address 192.168.5.5
R1(config-if)# ip address 192.168.5.9 255.255.255.252
B. R1(config)#no ip host R1
R1(config)# ip host R2 192.168.5.6 255.255.255.252
C. R1(config)#no hostname R2
R1(config)# hostname R1
D. R2(config)#int S1
R1(config-if)#no ip address 192.168.5.5
R1(config-if)# ip address 192.168.5.9 255.255.255.0

Correct Answer: B

Explanation:
Both routers have been configured with the ip host command. This command creates a name to IP address mapping, thereby enabling the pinging of the device by address. On R1,
the mapping is incorrect and needs to be corrected. Currently it is configured as ip host R1 192.168.5.6. It is currently mapping its own name to the IP address of R2.
To fix the problem, you should remove the incorrect IP address mapping and create the correct mapping for R2, as follows:
R1(config)#no ip host R1
R1(config)# ip host R2 192.168.5.6 255.255.255.252
Once this is done, the ping on R2 will succeed.
The IP address of the S1 interface on R1 does not need to be changed to 192.168.5.9 /30. In fact, if that is done the S1 interface on R1 and the S1 interface in R2 will no longer be in
the same network. With a 30-bit mask configured, the network they are currently in extends from 192.168.5.4 – 192.168.5.7. They are currently set to the two usable addresses in that
network, 192.168.5.5 and 192.168.5.6.
The hostnames of the two routers do need to be set correctly using the hostname command for the ping to function, but they are correct now and do not need to be changed.
The subnet mask of the S1 interface on R2 does not need to be changed to 255.255.255.0. The mask needs to match that of R1, which is 255.255.255.252.
Objective:
Infrastructure Services
Sub-Objective:
Troubleshoot client connectivity issues involving DNS