Router(config)# ip dhcp excluded-address
Router(config)# ip dhcp pool name
Router(dhcp-config)# network [mask | /prefix-length]
Router(dhcp-config)# default-router
Router(dhcp-config)# lease {days [hours][minutes] | infinite}
http://www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfdhcp.html#wp1000985 for further parameters