The ip helper-address command does what?

A.
assigns an IP address to a host

B.
resolves an IP address from a DNS server

C.
relays a DHCP request across networks

D.
resolves an IP address overlapping issue

Explanation:
http://cisconet.com/tcpip/dhcp/107-how-to-use-ip-helper-address-to-connect-remote-dhcpserver.html
When the DHCP client sends the DHCP request packet, it doesn’t have an IP address. So it uses
the all-zeroes address, 0.0.0.0, as the IP source address. And it doesn’t know how to reach the
DHCP server, so it uses a general broadcast address, 255.255.255.255, for the destination.
So the router must replace the source address with its own IP address, for the interface that
received the request. And it replaces the destination address with the address specified in the
ip helper-address command. The client device’s MAC address is included in the payload of the
original DHCP request packet, so the router doesn’t need to do anything to ensure that the
server receives this information.