Configuring Dynamic IP Address on Cisco Edge Router Interface

FastEthernet 0/0 Interface Configuration for Dynamic IP Address


You are configuring your edge routers interface with a public IP address for Internet connectivity. The router needs to obtain the IP address from the service provider dynamically.

Which command is needed on interface FastEthernet 0/0 to accomplish this?



Click on the arrows to vote for the correct answer

A. B. C. D. E.


The correct command to obtain an IP address from a service provider dynamically on the FastEthernet 0/0 interface of a Cisco router is "ip address dhcp". Therefore, the correct answer is D.


When connecting to the internet, the edge router needs a public IP address to communicate with other devices on the internet. Internet Service Providers (ISPs) often assign dynamic public IP addresses to their clients, meaning that the IP address assigned to a client may change periodically. In such cases, the edge router must obtain an IP address dynamically from the ISP.

To configure an interface to obtain an IP address from a DHCP server, use the "ip address dhcp" command on the interface. This command instructs the router to obtain its IP address, subnet mask, default gateway, and DNS server addresses from a DHCP server. The router sends a DHCP request to the DHCP server, which responds with the required configuration information.

The other commands mentioned in the question are used for different purposes:

  • "ip default-gateway" is used to configure the default gateway IP address on a router.
  • "ip route" is used to configure static routes on a router.
  • "ip default-network" is a deprecated command that was used to specify the default network for a router.
  • "ip address dynamic" is not a valid Cisco IOS command.