OSPF troubleshooting: A network administrator configures: Router(config)# router ospf 1 Router(config-router)# network 10.0.0.0 255.0.0.0 area 0 but still sees no OSPF routes in the routing table. What configuration mistake was made?

Introduction / Context:
This question evaluates understanding of OSPF configuration syntax and the distinction between subnet masks and wildcard masks. OSPF requires a wildcard mask, not a standard subnet mask, when configuring networks under the routing process.

Given Data / Assumptions:

• Configuration: Router(config)# router ospf 1
• Router(config-router)# network 10.0.0.0 255.0.0.0 area 0
• OSPF not forming adjacencies, no routes visible

Concept / Approach:
The “network” command in OSPF uses a wildcard mask, which is the inverse of a subnet mask. For network 10.0.0.0/8, the subnet mask is 255.0.0.0 but the wildcard mask should be 0.255.255.255.

Step-by-Step Solution:

Verification / Alternative check:
Run show ip ospf interface to see if interfaces are participating. With wrong wildcard mask, no interfaces will appear under OSPF.

Why Other Options Are Wrong:

• OSPF area: Area 0 is valid for backbone.
• Process ID: Locally significant only; any number works.
• AS configuration: Not relevant; OSPF is IGP, not dependent on AS configuration.
• Router ID: If missing, router automatically selects highest IP; not the cause here.

Common Pitfalls:
Confusing wildcard mask with subnet mask; forgetting that OSPF requires inverse masks.

Final Answer:
The wildcard mask is incorrect.