Troubleshooting Subnet Lease Issues

A technician has deployed an additional DHCP server for redundancy.

Clients in certain subnets are not receiving DHCP leases from the new DHCP server.

Which of the following is the MOST likely cause?

A.

The new DHCP server's IP address was not added to the router's IP helper list.

B.

The new DHCP server is not receiving the requests from the clients.

C.

The ARP cache of the new DHCP server needs to be updated.

D.

The ARP table on the router needs to be cleared.

A.

The most likely cause of clients in certain subnets not receiving DHCP leases from the new DHCP server is that the new DHCP server's IP address was not added to the router's IP helper list.

DHCP (Dynamic Host Configuration Protocol) is used to automatically assign IP addresses and other network configuration parameters to clients on a network. DHCP servers can be configured for redundancy, so that if one server fails, another can take over.

However, in order for clients to receive DHCP leases from the new server, the router needs to know where to forward DHCP requests. This is typically done using the IP helper feature, which allows the router to forward DHCP requests to specific DHCP servers on other subnets.

If the new DHCP server's IP address was not added to the router's IP helper list, the router will not forward DHCP requests to the new server. As a result, clients in certain subnets will not receive DHCP leases from the new server, even though it is operational.

Option B, that the new DHCP server is not receiving requests from clients, is less likely to be the cause, because the new DHCP server is operational, and therefore should be receiving requests.

Option C, that the ARP cache of the new DHCP server needs to be updated, is also less likely to be the cause, because ARP (Address Resolution Protocol) is used to map IP addresses to MAC addresses, and does not have a direct impact on DHCP.

Option D, that the ARP table on the router needs to be cleared, is also less likely to be the cause, because clearing the ARP table would not necessarily resolve the issue of clients not receiving DHCP leases from the new server.