Lab 33: Troubleshooting and Configuring DHCP (Client-Server Router-Based)

Lab Objective:

The objective of this lab exercise is for you to learn how to implement DHCP in a Cisco router both as a DHCP server and a DHCP client.

Lab Purpose:

Configuring DHCP is a very important task for every network engineer, as this protocol is in charge of the assignment of IP addresses. In this lab, you will learn the steps required to both provide and learn an IP address via DHCP. As a Cisco engineer, as well as in the Cisco CCNA exam, you will be expected to know how to implement DHCP in your network.

Certification Level:

This lab is suitable for ICND1 certification exam preparation.

Lab Difficulty:

This lab has a difficulty rating of 6/10.

Readiness Assessment:

When you are ready for your certification exam, you should complete this lab in no more than 20 minutes.

Lab Topology:

Please use the following topology to complete this lab exercise:

Note: R1 will be the DHCP server and R2 will be configured as a DHCP client to obtain an IP address on its Gig0/0 interface.

Task 1:

Configure the hostnames on R1 and R2 as illustrated in the topology.

Task 2:

Configure the IP addresses on the Gig0/0 interface of R1 as illustrated in the topology.

Note: R2 will obtain the IP of its Gigabit interface via DHCP.

Task 3:

Configure a DHCP pool on R1 to provide an IP address to the different devices connected on its interface Gig0/0 with the following settings:

  • DHCP pool name: Pool-1
  • DHCP subnet: 192.168.10.0/24
  • DHCP DNS server: 4.2.2.2
  • DHCP default gateway: 192.168.10.1

Note: Make sure you exclude the 192.168.10.1 address from the DHCP pool.

Task 4:

Configure R2 interface Gig0/0 to obtain its IP address via DHCP.

Task 5:

Confirm the assignment of the IP address on both the DHCP client and DHCP server running the following commands:

On the DHCP server:

  • show ip dhcp pool (to check the DHCP configuration)
  • show ip dhcp binding (to check the database of IPs provided and the clients that have obtained each of those IPs)

On the DHCP client:

  • show ip interface brief (to confirm that it gets an IP and it’s obtained via DHCP)

Task 6:

Now break the lab in a few ways. Start from the beginning (reload the routers):

  • Don’t exclude the IP address.
  • Miss off the ip address dhcp command on the host.
  • Configure the wrong network range.
  • Configure the correct network range but with the subnet of 255.255.255.252 (so you only have two host addresses).

Configuration and Verification

Task 1:

For reference information on configuring hostnames, please refer to earlier labs.

Task 2:

R1#conf t 
Enter configuration commands, one per line.  End with CTRL/Z. 
R1(config)#int gig0/0 
R1(config-if)#no shutdown 
R1(config-if)#ip add 192.168.10.1 255.255.255.0 
R1(config-if)#end

Task 3:

R1#config t 
R1(config)#ip dhcp pool Pool-1 
R1(dhcp-config)#network 192.168.10.0 255.255.255.0 
R1(dhcp-config)#dns-server 4.2.2.2 
R1(dhcp-config)#default-router 192.168.10.1 
R1(dhcp-config)#exit 
R1(config)#ip dhcp excluded-address 192.168.10.1

Task 4:

R2#config t 
Enter configuration commands, one per line.  End with CTRL/Z. 
R2(config)#int gig0/0 
R2(config-if)#ip address dhcp 
R2(config-if)#exit

Task 5:

On the server side:

R1#sh ip dhcp pool Pool Pool-1 :

Utilization mark (high/low)    : 100 / 0 
Subnet size (first/next)       : 0 / 0 
Total addresses                : 254 
Leased addresses               : 1 
Pending event                  : none 
1 subnet is currently in the pool :
 Current index      IP address range                Leased addresses 
192.168.10.3       192.168.10.1 - 192.168.10.254    1 

R1#sh ip dhcp binding 

Bindings from all pools not associated with VRF: 
IP address    Client-ID/           Lease expiration       Type Hardware address/ User name
192.168.10.2  0063.6973.636f.2d63. Mar 02 2002 08:14 PM   Automatic 3030.322e.3235.6362. 2e30.3030.302d.4661. 302f.30 

On the client side: 


R2#show ip interface brief 
Interface          IP-Address      OK?  Method   Status     Protocol 
FastEthernet0/0    192.168.10.2    YES  DHCP     up         up

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