DHCP stands for Dynamic Host Configuration Protocol. Basically it’s a mechanism which assigns IP addresses to computers dynamically. Usually DHCP is a service running on a server machine in the network in order to assign dynamic IP addresses to hosts. All Cisco 800 series models have the ability to work as DHCP servers, thus assigning addresses to the internal LAN hosts. Without a DHCP server in the network, you would have to assign IP addresses manually to each host. These manually assigned addresses are also called “static IP addresses”.

In this post I will show you how to configure a Cisco 851 or 871 router to work as DHCP server. The same configuration applies for other 800 series models as well.

Router> enable

Router# config t

! define an IP address pool name and range
Router(config)# ip dhcp pool LANPOOL

! define a network range for the addresses that will be assigned
Router(dhcp-config)# network 192.168.1.0 255.255.255.0

! define a dns name to assign to clients
Router(dhcp-config)# domain-name mycompany.com

! define a default gateway for the clients
Router(dhcp-config)# default-router 192.168.1.1

! define the dns server for the clients
Router(dhcp-config)# dns-server 100.100.100.1

! define a WINS server if you have one
Router(dhcp-config)# netbios-name-server 192.168.1.2
Router(dhcp-config)# exit

!The following addresses will not be given out to clients
Router(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.10

Related posts:

1. Forwarding a DHCP Request using Cisco ip helper-address command
2. Cisco Router 851 – 871 Interfaces and Basic Configuration
3. Cisco 800 Series Router Models
4. How to configure a Cisco Layer 3 switch-InterVLAN Routing
5. How to Configure a Cisco ASA 5510 Firewall – Basic Configuration Tutorial