Refer to the exhibit. If no router ID was manually configured, what would router R1 use as its OSPF router ID?

In OSPF (Open Shortest Path First), the router ID is chosen based on one of the following methods, in order of preference:

1. The router ID manually configured by an administrator.
2. The highest IP address of any of the router’s active interfaces.
3. The highest IP address of any of the router’s loopback interfaces.

If no router ID is manually configured, OSPF will choose the highest IP address of any of the router’s active interfaces. Since loopback interfaces are considered more stable (they are always up if configured), the IP address of a loopback interface is preferred over physical interfaces.

In the provided exhibit, we see the following IP addresses:

• G0/0: 10.1.0.1/16
• Lo0: 192.168.1.100
• The OSPF network: 10.0.0.0/16
• The external network: 209.165.201.1/29

Given these choices, the highest IP address on an active interface is 192.168.1.100, which is the IP address of the loopback interface Lo0. Therefore, router R1 would use 192.168.1.100 as its OSPF router ID.