Which of the following commands will enable the DHCP and relay services on a Cisco router?
A. RouterA(config)# service dhcp
B. RouterA(config)# dhcp enable
C. RouterA(config)# enable dhcp
D. RouterA(config-if)# dhcp enable
E. RouterA(config-if)# service dhcp
Using the service dhcp command at global configuration mode will enable the DHCP and relay services on
a Cisco router. By default, these services are already enabled on the router, but they can be disabled using
the no service dhcp command. Before the DHCP service can actually function, a pool of addresses must be
created and any statically defined addresses (such as the router itself) must be excluded. If the router has
two interfaces and needs to issue addresses on both interfaces two pools and two exclusion statements
must be present.
Below is an example of a complete configuration taken from a partial output of the show run command. This
router has two interfaces 10.0.0.1/24 and 192.168.5.1/24, creating the need for two pools and two exclusion
statements. It excludes the address ranges 10.0.0.1-10.0.0.5 from the 10.0.0.0/24 pool and excludes
192.168.5.1-192.168.5.5 from the 192.168.5.0/24 pool, and creates a pool for 10.0.0./24 and
The commands RouterA(config)# dhcp enable and RouterA(config)# enable dhcp are incorrect because the
syntax is incorrect.
The command RouterA(config-if)# dhcp enable is incorrect because the syntax is incorrect and because it
is executed in interface configuration mode. Enabling DHCP is done at the global prompt.
The command RouterA(config-if)# service dhcp is incorrect because it is executed in interface configuration
mode. Enabling DHCP is done at the global prompt
Layer 3 Technologies
Identify, configure, and verify IPv4 addressing and subnetting
Cisco > IP Addressing: DHCP Configuration Guide, Release 15M&T > DHCP Overview
Cisco > Cisco IOS IP Addressing Services Command Reference > service dhcp