200-301 Question 25
Single answerA network administrator is troubleshooting connectivity issues between two endpoints in a corporate network. The endpoints are connected to the same Layer 2 switch. The administrator verifies that both endpoints are in the same VLAN. However, the endpoints cannot communicate. Which of the following is the MOST likely cause of the issue?
- A
Duplicate IP addresses on the two endpoints
- B
Incorrect subnet masks configured on the endpoints
- C
Port security is blocking traffic on the switch
- D
The switch does not have a default gateway configured
Show answer and explanation
Correct answer: B
Explanation
In this scenario, the endpoints are in the same VLAN but cannot communicate. The most likely cause is that the subnet masks are incorrectly configured, causing the endpoints to treat each other as if they are in different subnets. This would prevent direct Layer 3 communication even within the same VLAN.
- A. Incorrect.
Duplicate IP addresses would cause an IP conflict, but it would not prevent communication entirely as long as one endpoint can respond. This is not the most likely cause in this scenario.
- B. Correct.
Incorrect subnet masks would cause the endpoints to believe they are in different subnets, even though they are in the same VLAN. This would prevent communication between the endpoints, making it the most likely cause.
- C. Incorrect.
Port security could block traffic, but this would typically result in the port being shut down or restricted. The scenario does not mention any such indications.
- D. Incorrect.
A default gateway is not required for communication between endpoints in the same VLAN, as the traffic does not leave the local subnet. This is not relevant to the issue.