Cisco CCNA mock exam questions sample test – Question 86

.You would like for Router25 in your OSPF network to become the DR. You execute the show ip ospf interface command, receiving the output shown below.
You assign an IP address of 192.168.5.6 to the Ethernet1 interface of Router25 and enable the interface. However, Router25 does NOT become the designated router.
What additional command must you execute to cause Router25 to become the DR?

A. Router25(config-router)# network 192.168.5.0 0.0.0.255 area 0
B. Router25(config-router)# network 192.168.5.0 0.0.0.255 area 1
C. Router25(config-router)# network 192.168.5.0 255.255.255.0 area 0
D. Router25(config)# network 192.168.5.0 0.0.0.255 area 0

Correct Answer: A

Explanation:
The command Router25(config-router)# network 192.168.5.0 0.0.0.255 area 0 must be executed to enable Router25 to become the DR. For an interface to be considered in the DR
election, it must be advertised in OSPF. Otherwise, it is not participating in OSPF routing and you may be faced with the situation illustrated by the output of the shown ip ospf interface
command below:
The RID of Router25, 225.16.33.4, is higher than that of the current DR, which has an RID of 172.16.10.1. Despite that fact, Router 25 did not become the DR because the 225.0.0.0
network has not been advertised. This could be verified by executing the show ip protocols command as shown below:
As only the 10.0.0.0 network is being advertised, the 225.16.33.4 IP address will not be a factor in the DR election.
The command Router25(config-router)# network 192.168.5.0 0.0.0.255 area 1 is incorrect because it references area 1 instead of area 0, which is the area in use in this scenario.
The command Router25(config-router)# network 192.168.5.0 255.255.255.0 area 0 is incorrect because it uses a regular mask instead of a wildcard mask. Network commands in
OSPF must use a wildcard mask.
The command Router25(config)# network 192.168.5.0 0.0.0.255 area 0 is incorrect because it is executed at the global configuration, router25(config)#, prompt rather than the OSPF
configuration prompt, router25(config-router)#.
Objective:
Routing Fundamentals
Sub-Objective:
Configure, verify, and troubleshoot single area and multi-area OSPFv2 for IPv4 (excluding authentication, filtering, manual summarization, redistribution, stub, virtual-link, and LSAs)
References:
Cisco > Home > Support > Technology Support > IP > IP Routing > Technology Information > Technology White paper > OSPF Design Guide