Configure Cisco router as a DHCP client

Cisco routers can be configure as both DHCP servers and DHCP clients. An interface on a router that connects to the Internet Service Provider (ISP) is often configured as a DHCP client. This way, the ISP can provide the IP information to the client device.

To configure an interface as a DHCP client, the ip address dhcp interface mode command is used. Consider the following example:

We have a small network consisting of a router and a DHCP server. We want to configure the interface Gi0/0 on the router as a DHCP client. This is how this is done:

R1(config)#int Gi0/0
R1(config-if)#ip address dhcp

We can verify that the Gi0/0 interface has indeed got its IP address from the DHCP server by running the show ip int brief command:

R1#show ip int brief
Interface              IP-Address      OK? Method Status                Protocol 
GigabitEthernet0/0     192.168.0.1     YES DHCP   up                    up 
GigabitEthernet0/1     unassigned      YES unset  administratively down down

The DHCP keyword in the method column indicates that the IP information were obtained by the DHCP server.

NOTE
If you want to configure a Cisco switch as a DHCP client, the ip address dhcp command is used under the VLAN 1 configuration mode.