A Cisco router running OSPFv2 has no manually configured router ID (`router-id` command). The router has the following active and operational interfaces configured with IP addresses:
- Loopback 0: 10.10.10.1/32
- Loopback 1: 172.16.50.1/32
- GigabitEthernet0/0: 192.168.1.1/24
- GigabitEthernet0/1: 192.168.2.1/24
What IP address will OSPF automatically select as the OSPF Router ID?
Answer: 172.16.50.1
Answer
172.16.50.1
In OSPFv2, the router ID election order is: 1) Manually configured router ID (`router-id` command), 2) Highest IP address among active loopback interfaces, and 3) Highest IP address among active non-loopback (physical) interfaces. Because active loopbacks exist and no manual router ID is specified, OSPF chooses the highest loopback IP address, which is 172.16.50.1.
Step-by-Step Solution
Key Concept
OSPFv2 Router ID Election Order