2.7 DHCP and Easy IP
2.7.3 Configuring IOS DHCP server
Although it is enabled by default on versions of the Cisco IOS that support it, the DHCP server process can be re-enabled by using the service dhcp global configuration command. The no service dhcp command disables the server.

Like NAT, DHCP server requires that the administrator define a pool of addresses. In Figure , the
ip dhcp pool command defines which addresses will be assigned to hosts.

The first command,
ip dhcp pool room12, creates a pool named room12 and puts the router in a specialized DHCP configuration mode. In this mode, you use the network statement to define the range of addresses to be leased. If you want to exclude specific addresses on this network, you must return to global configuration mode, as shown in Figure .

This
ip dhcp excluded-address command configures the router to exclude 172.16.1.1 through 172.16.1.10 when assigning addresses to clients. You may choose to use the ip dhcp excluded-address command to reserve addresses that are statically assigned to key hosts.

Typically, you will want a DHCP server to configure much more than an IP address. Other IP configuration values can be set from the DHCP config mode, as shown in Figure .

IP clients will not get very far without a default gateway, which can be set by using the
default-router command. The address of the DNS server (dns-server) and WINS server (netbios-name-server) can be configured here as well. The IOS DHCP server can configure clients with virtually any TCP/IP information.

Figure lists the key IOS DHCP server commands, which you enter in DHCP pool configuration mode (identified by the
dhcp-config# prompt).

Using the EXEC mode commands shown in Figure can monitor DHCP server operation.