You are troubleshooting a network issue where two computers on the same subnet cannot communicate with each other. What could be the possible reasons for this problem, and how would you diagnose it?

The correct option is "Incorrect subnet mask." When two computers are on the same subnet but cannot communicate, it often indicates an issue with the subnet mask configuration. An incorrect subnet mask can cause devices to believe they are on different subnets, leading to communication issues. To diagnose this problem, you can check the subnet mask configuration on both computers and ensure they match the intended subnet.