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
default-router !-- gateway address
dns-server !-- DNS servers
netbios-name-server !-- WINS servers
lease 2 !-- lease time

!-- defining static binding to R2 using its client-id

ip dhcp pool STATIC
client-identifier 01cc.010d.f000.00

!-- exclude server and static addresses from the dynamic pool

ip dhcp excluded-address
ip dhcp excluded-address
ip dhcp excluded-address
p dhcp excluded-address

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 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 01cc.010d.f000.00 Infinite Manual

R2 gets its domain-name dynamically from R1

R2#sh ip domain

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 to network

C is directly connected, FastEthernet0/0 is subnetted, 1 subnets
C is directly connected, Loopback0
S* [254/0] via

R2 learns Primary and secondary DNS servers from R1

R2#ping xyz.comTranslating ""...domain server ( (
% 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

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