Final answer:
The correct commands to change the administrative distance of OSPF to 25 are to enter the OSPF router configuration mode and then apply the 'distance' command: 'router ospf 1' followed by 'distance 25'.
Step-by-step explanation:
To change the administrative distance of OSPF to a specific value, you need to use the 'distance' command within the router ospf configuration mode on a Cisco router. The correct sequence of commands to change the administrative distance of OSPF from 110 to 25 (given that the OSPF process ID is 1) is to first enter the router configuration mode specifically for OSPF and then set the new administrative distance using the 'distance' command.
- router ospf 1
- distance 25
Therefore, the correct answer from the given options is 'a. router ospf 1 distance 25'.
It is crucial for network engineers to understand the implications of changing the administrative distance as it influences the route selection process when multiple protocols provide route information for the same destination.