200-301 Question 378
Single answerA network administrator is configuring a DHCP relay agent on a router to forward DHCP requests from a subnet without a DHCP server to a centralized DHCP server located on a different subnet. After completing the configuration, the clients on the subnet are still not receiving IP addresses. Which step is MOST likely missing or incorrect in the configuration?
- A
The 'ip helper-address' command is not configured on the router interface connected to the client subnet.
- B
The DHCP server address is not reachable from the router.
- C
The router interface connected to the DHCP server is missing an IP address.
- D
The 'service dhcp' command is not enabled globally on the router.
Show answer and explanation
Correct answer: A
Explanation
In a DHCP relay configuration, the 'ip helper-address' command is critical to instruct the router to forward DHCP requests from the client subnet to the centralized DHCP server. Without this configuration, the DHCP requests will not leave the local subnet, resulting in clients failing to receive IP addresses.
- A. Correct.
The 'ip helper-address' command is required to configure the router as a DHCP relay agent. Without this command, the router will not forward DHCP packets to the DHCP server.
- B. Incorrect.
While the DHCP server must be reachable, this issue would result in different symptoms, such as timeouts during packet forwarding, rather than the complete lack of DHCP operation described in the scenario.
- C. Incorrect.
The router interface connected to the DHCP server must have an IP address for routing, but the question does not indicate connectivity issues to the server. This is less likely to be the issue in this scenario.
- D. Incorrect.
The 'service dhcp' command is required only when the router is configured as a DHCP server itself. Since the router is acting as a DHCP relay in this case, this command is not relevant.