Sometimes, Cisco routers in small office/home office (SOHO) and branch sites have to be configured as DHCPv4 clients in a similar manner to client computers. The method used depends on the ISP. However, in its simplest configuration, the Ethernet interface is used to connect to a cable or DSL modem. To configure an Ethernet interface as a DHCP client, use the ip address dhcp interface configuration mode command.
In Figure 1, assume that an ISP has been configured to provide select customers with IP addresses from the 209.165.201.0/27 network range. After the G0/1 interface is configured with the ip address dhcp command, the show ip interface g0/1 command confirms that the interface is up and that the address was allocated by a DHCPv4 server.
Use the Syntax Checker in Figure 2 to configure the interface that is connected to the ISP to acquire an address from the DHCP server.