Cisco IOS DHCP Server

Don't wanna get another box just for DHCP? Using your routers or switches as DHCP server might be a choice for you. :)

! Your exclude range
ip dhcp excluded-address 10.3.1.1 10.3.1.20

! Define your pool
ip dhcp pool MyPool
network 10.3.1.0 255.255.255.0
default-router 10.3.1.1
option 150 ip 10.3.1.1
dns-server 10.1.1.20

A trick if you want to restart the DHCP server:
no service dhcp
service dhcp