How-TO: Configure DHCP on a CISCO router

This post is about configuring a CISCO router to act as a DHCP server in your network.

Task1: Configure R1 to act as a DHCP server and provide all network information to hosts in the LAN dynamically. (R1 and R2 are directly connected via Ethernet)

Server Configuration (R1)

!– enable dhcp server (default) service dhcp ! — defining DHCP pool with all network information ip dhcp pool OFFICE network 192.168.12.0 255.255.255.0 domain-name networkers-online.com default-router 192.168.12.1 !– gateway address dns-server 192.168.12.100 192.168.12.101 !– DNS servers netbios-name-server 192.168.12.99 !– WINS servers lease 2 !– lease time !– defining static binding to R2 using its client-id ip dhcp pool STATIC host 192.168.12.2 255.255.255.0 client-identifier 01cc.010d.f000.00 !– exclude server and static addresses from the dynamic pool ip dhcp excluded-address 192.168.12.1 ip dhcp excluded-address 192.168.12.100 192.168.12.101 ip dhcp excluded-address 192.168.12.200 p dhcp excluded-address 192.168.12.2

Client Configuration:

interface FastEthernet0/0 ip address dhcp client-id FastEthernet0/0

Troubleshooting and verfication:

IP address is assigned dynamically to R2

!– R2 f0/0 address is assigned via DHCP R2(config-if)#do sh ip int b Interface IP-Address OK? Method Status Protocol FastEthernet0/0 192.168.12.2 YES DHCP up up !– R1 bindings has R2 as a static entry R1#sh ip dhcp binding Bindings from all pools not associated with VRF: IP address Client-ID/ Lease expiration Type Hardware address/ User name 192.168.12.2 01cc.010d.f000.00 Infinite Manual

R2 gets its domain-name dynamically from R1

R2#sh ip domain networkers-online.com

R2 sets R1 as a default gateway using a floating static route

R2#sh ip route Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2 E1 – OSPF external type 1, E2 – OSPF external type 2 i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2 ia – IS-IS inter area, * – candidate default, U – per-user static route o – ODR, P – periodic downloaded static routeGateway of last resort is 192.168.12.1 to network 0.0.0.0 C 192.168.12.0/24 is directly connected, FastEthernet0/0 2.0.0.0/24 is subnetted, 1 subnets C 2.2.2.0 is directly connected, Loopback0 S* 0.0.0.0/0 [254/0] via 192.168.12.1

R2 learns Primary and secondary DNS servers from R1

R2#ping xyz.comTranslating “yahoo.com”…domain server (192.168.12.100) (192.168.12.101) % Unrecognized host or address, or protocol not running.

for more information on how to configure DHCP features consult the following link CISCO IOS DHCP Server