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?
The correct command to obtain a dynamic IP address from a service provider on a Cisco edge router interface is the "ip address dhcp" command.
This command enables the router to obtain its IP address, subnet mask, default gateway, and other configuration parameters from a DHCP server provided by the service provider.
Here's an example of how to configure this command on a FastEthernet interface:
Router(config)# interface FastEthernet 0/0 Router(config-if)# ip address dhcp
Once the interface is configured with the "ip address dhcp" command, the router will send a DHCP request to the service provider's DHCP server, which will respond with the necessary configuration information. The router will then use this information to configure the interface and establish Internet connectivity.
Note that the other options listed in the question are not correct for this scenario:
The "ip default-gateway" command sets the default gateway IP address for the router, which is not needed in this scenario since the router will obtain its default gateway address dynamically from the DHCP server.
The "ip route" command is used to manually configure static routes on the router, which is not relevant to this scenario since the router will obtain its IP address and default gateway dynamically.
The "ip default-network" command is used to set a default network for the router, which is not necessary in this scenario since the router will obtain its IP address and default gateway dynamically.
The "ip address dynamic" command does not exist on Cisco routers, so it is not a valid option.