Question

If interface Fa0/0 on RouterB has the ip helper-address configuration command in its running configuration, which of the following statements are true?

1) The router will forward DHCP requests to the specified IP address
2) The router will forward DNS requests to the specified IP address
3) The router will forward ARP requests to the specified IP address
4) The router will forward ICMP requests to the specified IP address

Answer 1

The ip helper-address command on a router interface forwards DHCP requests to a specified IP address, but does not forward DNS, ARP, or ICMP requests.

Step-by-step explanation:

When the ip helper-address configuration command is used on an interface in a Cisco router, it enables the router to forward certain kinds of broadcast traffic as unicast to a specified IP address. This is typically used to forward Dynamic Host Configuration Protocol (DHCP) requests from clients to a DHCP server that is not on the same subnet as the clients.

The correct statement in this case is: 1) The router will forward DHCP requests to the specified IP address. This is because the ip helper-address command is specifically intended to forward DHCP requests along with some other types of broadcast traffic, such as TFTP (Trivial File Transfer Protocol) and BootP (Bootstrap Protocol).

However, the ip helper-address command does not forward DNS requests, ARP requests, or ICMP requests. These protocols either do not use broadcasts for their normal operation (DNS, ICMP) or they are not included in the list of protocols forwarded by the ip helper-address command (ARP).