Back to course

Configuring Cisco IOS as a DHCP Server and Relay Agent

CCNA: 0 to Hero - Comprehensive Network Engineering Bootcamp

Lesson 43: Configuring Cisco IOS as DHCP Server and Relay Agent

Cisco DHCP Server Configuration

  1. Exclude Addresses: Define addresses that should not be leased (e.g., router interfaces, servers).
  2. Create the Pool: Define the network, default gateway, and DNS servers.

ios Router(config)# ip dhcp excluded-address 192.168.10.1 192.168.10.10

Router(config)# ip dhcp pool STAFF_VLAN Router(config-dhcp)# network 192.168.10.0 255.255.255.0 Router(config-dhcp)# default-router 192.168.10.1 Router(config-dhcp)# dns-server 8.8.8.8 4.4.4.4 Router(config-dhcp)# lease 7

DHCP Relay Agent (ip helper-address)

If the DHCP server is on a remote subnet, the router connected to the client subnet must act as a relay agent.

ios ! Assume DHCP server is 172.16.1.1 and clients are on G0/1 Router(config)# interface GigabitEthernet 0/1 Router(config-if)# ip helper-address 172.16.1.1

This command changes the DHCP broadcast into a unicast packet destined for the server, allowing it to traverse the router.