A network engineer is administering an active OSPFv2 routing process on router R1. The router currently has the following interface IP addresses and operational statuses:
- Loopback 0: (Status: Up, Line Protocol: Down)
- Loopback 1: (Status: Up, Line Protocol: Up)
- GigabitEthernet0/0: (Status: Up, Line Protocol: Up)
- GigabitEthernet0/1: (Status: Up, Line Protocol: Up)
While OSPFv2 process 1 is actively running with active neighbor adjacencies, the engineer executes the command `router-id 1.1.1.1` under the OSPF router configuration mode. Which TWO statements accurately describe the resulting OSPF Router ID behavior and operational state on R1? (Select TWO.)
- The currently active OSPF Router ID will remain unchanged until the OSPF process is explicitly reset or the router is rebooted.Answer
- Once the OSPF process is cleared, the statically configured value 1.1.1.1 will take precedence over all loopback and physical interface IP addresses.Answer
- CThe active OSPF Router ID immediately changes to 1.1.1.1 across all established neighbors without dropping existing adjacencies.
- DIf the manual router ID command is removed and the process is reset, Loopback 0 (192.168.10.1) will be chosen because it has the highest numeric IP address among loopbacks.
Answer
The active OSPF Router ID will remain unchanged until the process is reset or rebooted, and once cleared, the manually configured router-id command takes precedence over all interface IP addresses.
In OSPFv2, explicit manual configuration using the `router-id` command takes top priority over all loopback and physical interfaces once applied. However, OSPF Router ID evaluation is strictly non-preemptive on an active process. Changing the Router ID while neighbors are active will store the configured value in running-config without changing the operational Router ID until the OSPF process is cleared via `clear ip ospf process` or the device reboots.
Step-by-Step Solution
Key Concept
OSPFv2 Router ID Selection Logic & Non-Preemptive Execution