200-301 Question 330
Single answerA network administrator is configuring OSPFv2 in a single area (Area 0) on three routers: R1, R2, and R3. After the configuration, R1 is unable to establish a neighbor relationship with R2, but R2 and R3 have successfully formed an adjacency. The following configuration was applied on R1:
router ospf 1
network 192.168.1.0 0.0.0.255 area 0
network 192.168.2.0 0.0.0.255 area 0
The IP addresses configured on R1 and R2 interfaces are:
- R1: 192.168.1.1/24 and 192.168.3.1/24
- R2: 192.168.1.2/24 and 192.168.3.2/24
What could be the cause of the issue?
- A
The OSPF process ID on R1 does not match the OSPF process ID on R2.
- B
The network statement for 192.168.3.0/24 is missing on R1.
- C
R1 and R2 are using different OSPF areas for their network statements.
- D
There is an IP address mismatch between R1 and R2 on their respective interfaces.
Show answer and explanation
Correct answer: B
Explanation
OSPF requires that both routers on a link have network statements that include the subnet on which they are connected. In this case, the 192.168.3.0/24 subnet is missing in the OSPF configuration of R1, which prevents the OSPF adjacency from forming between R1 and R2 on that subnet. Adding the statement network 192.168.3.0 0.0.0.255 area 0 to R1 will resolve the issue.
- A. Incorrect.
OSPF process IDs do not need to match between routers to form a neighbor relationship. The issue is not related to the process ID.
- B. Correct.
R1 is missing the network statement for 192.168.3.0/24, which prevents OSPF from establishing a neighbor relationship on the 192.168.3.0/24 subnet.
- C. Incorrect.
Both R1 and R2 are configured to use Area 0, so there is no area mismatch in this scenario.
- D. Incorrect.
The IP addresses on the interfaces are configured correctly and belong to the same subnets, so there is no IP address mismatch.