Configuration Issues

C

The Router ID (RID) is an important attribute in routing protocols such as OSPF, IS-IS, and BGP. The RID is used to uniquely identify a router in the network and is typically derived from a configured loopback interface address. In the case of Juniper routers, the RID is selected based on the highest IP address among all configured loopback interfaces by default.

Given the scenario where the RID of the router is being taken from the address of the management interface, it indicates that a suitable loopback address was not configured on the router. This means that the router is not able to select a loopback address with a higher IP address than the management interface, leading to the selection of the management interface IP address as the RID.

Option A suggests that the loopback address was configured with a /32 address, which means that the loopback address is configured with a subnet mask of 255.255.255.255, allowing only a single IP address. This does not affect the selection of the RID.

Option B suggests that the loopback address was not configured under [edit protocols ospf]. This would prevent OSPF from using the loopback address as the RID, but it does not explain why the management interface IP address is being used instead.

Option D suggests that the loopback address was configured under [edit routing-options]. This is the correct location to configure the loopback address as the RID in Juniper routers. However, if the loopback address is not configured correctly, the router may select the management interface IP address as the RID.

Therefore, the correct answer is option C - a suitable loopback address was not configured on the router. The solution would be to configure a loopback interface with an appropriate IP address and subnet mask to ensure that it has the highest IP address among all the configured loopback interfaces. Once this is done, the router will select the loopback address as the RID, and OSPF will function correctly.