Network & Security Engineering
  • My Training Course
  • Network Engineering
    • CompTIA Network+
      • OSI Model: Layers 1-7 (Functions & Devices)
      • TCP/IP Model: Layers & Protocols
      • Encapsulation & De-encapsulation Process in Networking
      • Star, Mesh, Bus, Ring, Hybrid
      • LAN, WAN, WLAN, MAN, CAN, PAN
      • IPv4 Addressing & Classes
      • CIDR Notation & Subnet Masks
      • Private vs. Public IPs
      • Common TCP & UDP Ports
      • Twisted Pair (CAT5e, CAT6, CAT7, etc.)
      • Fiber Optic Cables
      • Ethernet Frame Structure
      • Switches
      • Router
      • Traceroute Test
      • Setting Up a Wireless Network in Cisco Packet Tracer
    • CCNA
      • Cisco Systems History
      • Cisco Certification Roadmap
      • Cisco Router Port Naming
      • Configuring Hostname, Passwords, and Banners in GNS3
      • Setting Router Clocks in Cisco Devices
      • Assigning IP Addresses to Interfaces
      • How to Back Up and Restore Router Configurations with TFTP
      • SSH Configuration on a Cisco Router
      • Configuring Static Routes on Routers
      • Configuring RIP v2 and Verifying Routes
      • Configuring EIGRP
      • Implementing Single-Area OSPF
      • Implementing Multiple OSPF Areas
      • Troubleshooting with show ip route
      • Configuring Standard ACLs in Cisco Routers
      • Getting Internet in GNS3 using a Cisco Router
      • Securing Remote Management and Disabling Unnecessary Services
      • Setting up a DHCP Server on a Cisco Router
      • Creating VLANs and Assigning Ports
      • Blackhole VLAN
      • Configuring 802.1Q Trunking
      • Configuring SSH on a Cisco Switch
      • Configuring Router-on-a-stick (ROAS) for VLANs
      • Setting up Syslog for Network Monitoring
      • Serial Point-to-Point Overview
      • Point-to-Multipoint OSPF in Metro Ethernet WAN Network
      • Frame Relay Configuration
    • CCNP
      • OSPF Single Area Configuration
      • OSPF Multi-Area Configuration
    • GNS3
      • About GNS3
      • GNS3 Architecture
      • Windows Installation
      • Linux Installation
      • Cisco IOS images for Dynamips
      • Add Router IOS Image in GNS3
      • Add a Virtual Machine in GNS3
      • Upgrade The GNS3 VM
      • L2 Switching Simulation
      • L3 switching Simulation
      • Lab 01 : Connect 2 PCs
      • Lab 02 : Configuring Ethernet and Serial Interfaces
      • Lab 03 : Basic switch setup
      • Lab 04 : Basic router setup
      • Lab 05 : Connect Router to Cloud in GNS3
      • Lab 06 : Router Remote Access via Telnet
      • Lab 07 : Configure Static Route in GNS3
      • Lab 08 : Syslog Server for Cisco Router in GNS3
      • Lab 09 : DHCP configuration in GNS3
      • Lab 10 : PPP Configuration
      • Lab 11 : Configuring Switch Security Features
    • MTCNA
      • Module 1 : Introduction
        • History
        • Cisco vs. MikroTik
        • Training Programs
        • MikroTik RouterOS
        • MikroTik RouterBOARD
        • Product Categories
        • Product Naming
        • First Time Access
        • Winbox
        • Default Configuration
        • Neighbor Discovery
        • Command Line Interface
        • Router Identity
        • Upgrading RouterOS
        • Package Management
        • Users and Services
        • Reset Configuration
        • RouterOS Licensing
      • Module 2 : DHCP
        • Overview of DHCP
        • DHCP Client
        • DHCP Server
        • RouterOS ARP table
      • Module 3 : Bridging
        • OSI Model
        • Overview of Bridging
      • Module 4 : Routing
        • IP Addressing
        • Routing Concepts
        • Static routing
      • Module 5 : Wireless
        • Basics of Radio Waves
        • Wireless Agencies
        • 802.11a/b/g/n/ac Concepts
        • Setup a simple wireless link
        • Link Budget Calculation
        • Wireless Network Topologies
        • 2.4 GHz Band
        • 5 GHz Band
      • Module 6 : Firewall
        • Firewall Principles
        • Firewall (Input Chain)
      • Module 7 : QoS
        • Quality of Service
  • Network Administrator
    • Linux Commands
      • The ls command
      • The cd command
      • The cat command
      • The head command
      • The tail command
      • The pwd command
      • The touch Command
      • The cal Command
      • The uname command
      • The mkdir command
      • The gzip command
      • The who command
      • The man command
      • The passwd command
      • The w command
      • The whoami command
      • The cp command
    • Windows Server 2012
      • Windows Server 2012 - Home
      • Installation
      • Server Roles
      • PowerShell
      • Windows Firewall
      • Remote Desktop Management
      • Resource Monitor
      • Active Directory
      • Group Policy Overview
      • DC Accounts
      • DHCP Role
      • DNS Role
      • Primary Zones
      • Manage Records
      • IIS Overview
      • IIS Security
      • Sharing of Files
      • Print Server
    • VMware Workstation
      • Install VMware Workstation on Windows
      • Customize Network Settings in VMware Workstation
      • Install VMware Tools on Windows and Windows Server VMs
      • Configure Autologin for a Windows VM on VMware Workstation
      • Lab 01 - Install Windows 7 on a VMware Workstation
      • Lab 02 - Install CentOS 8 on a VMware Workstation
      • Lab 03 - Install Kali Linux on VMware Workstation
      • Lab 04 - Install The Mikrotik CHR On VMware Workstation​
      • Lab 05 - Install Ubuntu in VMware Workstation
      • Lab 06 - Installing GNS3 VM on VMware Workstation
      • Lab 07 - Install Windows Server 2012 R2 on VMWare Workstation
      • Lab 08 - Install Windows 10 in VMware Workstation
    • LPIC-1
      • 101.1 Determine and configure hardware settings
  • Security Engineering
    • Practical Packet Analysis
      • Network Traffic Analysis with Wireshark in GNS3
      • Echo Requests and Responses
      • Dynamic Host Configuration Protocol
      • Cisco Discovery Protocol
      • Routing Information Protocol
    • PRTG Network Monitoring
      • Overview of PRTG Network Monitor
      • Internet Uptime/Availability Monitoring
      • Configuring SNMP v2 on Cisco Devices
    • Classical Ciphers
      • Caesar Cipher
      • Atbash Cipher
      • Vigenère Cipher
      • Affine Cipher
      • Hill Cipher
      • Rail Fence Cipher
      • Scytale Cipher
      • Bacon's Cipher
      • Beaufort Cipher
      • ROT13
      • Gronsfeld Cipher
  • Web Development
    • HTML
      • What is HTML?
      • Basic HTML Structure
      • Headings and Paragraphs
      • Text Formatting Tags
      • Working with Links
      • Adding Images to a Webpage
      • Embedding Videos and Audio
      • Creating Lists
      • Building Tables
      • HTML Forms
Powered by GitBook
On this page
  • Scenario:
  • 1. Understanding DHCP
  • 2. Practical Scenario
  • 3. Network Topology
  • 4. Configuration Steps
  • 5. Verifying DHCP Configuration
  • 7. Troubleshooting Commands
  • Keywords
  1. Network Engineering
  2. CCNA

Setting up a DHCP Server on a Cisco Router

Nerd Cafe

PreviousSecuring Remote Management and Disabling Unnecessary ServicesNextCreating VLANs and Assigning Ports

Last updated 1 month ago

Scenario:

You are configuring a Cisco router as a DHCP server to dynamically assign IP addresses to client devices on a local network.

1. Understanding DHCP

DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses, subnet masks, default gateways, and other parameters to network devices. A Cisco router can function as a DHCP server, providing these settings to clients.

2. Practical Scenario

  • You are setting up a small office network.

  • The router will act as a DHCP server.

  • The local network uses the 192.168.1.0/24 subnet.

  • The router's interface (FastEthernet0/0) will be the gateway 192.168.1.1.

  • The DHCP server should assign addresses from 192.168.1.100 to 192.168.1.200.

  • Some devices (like a printer) will need static IP reservations.

3. Network Topology

4. Configuration Steps

Step 1: Enter Global Configuration Mode

Connect to the router via CLI (Console, SSH, or Telnet), then enter global configuration mode:

R1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#

Step 2: Exclude Reserved IP Addresses

Reserve specific IP addresses that should not be assigned by DHCP (e.g., for the router, printers, and servers):

R1(config)#ip dhcp excluded-address 192.168.1.1 192.168.1.10

  • 192.168.1.1 is the router’s IP.

  • 192.168.1.2 – 192.168.1.10 are reserved for static devices.

Step 3: Create a DHCP Pool

Define a DHCP pool named OFFICE_NETWORK:

R1(config)#ip dhcp pool OFFICE_NETWORK
R1(dhcp-config)#

Step 4: Define the Network and Subnet Mask

Specify the subnet for DHCP clients:

R1(dhcp-config)#network 192.168.1.0 255.255.255.0

Step 5: Set Default Gateway

Assign the router’s IP as the default gateway:

R1(dhcp-config)#default-router 192.168.1.1

Step 6: Define the DNS Server

Specify a DNS server (e.g., Google’s 8.8.8.8):

R1(dhcp-config)#dns-server 8.8.8.8

Step 7: Configure the Lease Time

Set a lease duration (e.g., 24 hours):

R1(dhcp-config)#lease 1 0 0

1 0 0 means 1 day, 0 hours, 0 minutes.

Step 8: Exit the DHCP Configuration

R1(dhcp-config)#exit
R1(config)#

Step9: Assign IP address to fastEthernet 0/0 (Connected to PC1)

R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address 192.168.1.1 255.255.255.0
R1(config-if)#no shutdown

Step 9: PC1 Configuration

PC1> ip dhcp
DORA IP 192.168.1.11/24 GW 192.168.1.1

PC1> show ip

NAME        : PC1[1]
IP/MASK     : 192.168.1.11/24
GATEWAY     : 192.168.1.1
DNS         : 8.8.8.8
DHCP SERVER : 192.168.1.1
DHCP LEASE  : 86395, 86400/43200/75600
MAC         : 00:50:79:66:68:00
LPORT       : 20008
RHOST:PORT  : 127.0.0.1:20009
MTU         : 1500

PC1>

Step 10: Printer (Static IP)

  • Manually set IP: 192.168.1.2, Gateway: 192.168.1.1.

  • Ensure it doesn’t request DHCP.

PC2> ip 192.168.1.2/24 192.168.1.1
Checking for duplicate address...
PC2 : 192.168.1.2 255.255.255.0 gateway 192.168.1.1

PC2> show ip

NAME        : PC2[1]
IP/MASK     : 192.168.1.2/24
GATEWAY     : 192.168.1.1
DNS         :
MAC         : 00:50:79:66:68:01
LPORT       : 20010
RHOST:PORT  : 127.0.0.1:20011
MTU         : 1500

PC2>

5. Verifying DHCP Configuration

1. Check the DHCP Configuration

R1#show ip dhcp pool

Pool OFFICE_NETWORK :
 Utilization mark (high/low)    : 100 / 0
 Subnet size (first/next)       : 0 / 0
 Total addresses                : 254
 Leased addresses               : 0
 Pending event                  : none
 1 subnet is currently in the pool :
 Current index        IP address range                    Leased addresses
 192.168.1.1          192.168.1.1      - 192.168.1.254     0
R1#

This shows the active DHCP pool and available IP addresses.

2. View DHCP Bindings (Leased IPs)

R1#show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address          Client-ID/              Lease expiration        Type
                    Hardware address/
                    User name
192.168.1.11        0100.5079.6668.00       Mar 23 2025 05:54 AM    Automatic
R1#

This displays assigned IP addresses and MAC addresses.

7. Troubleshooting Commands

  • Check if the DHCP service is running:

R1#show running-config | inclu
R1#show running-config | include dhcp
ip dhcp excluded-address 192.168.1.1 192.168.1.10
ip dhcp pool OFFICE_NETWORK
R1#

  • Debug DHCP process:

R1#debug ip dhcp server events
DHCP server event debugging is on

Keywords

DHCP, Cisco Router, IP Address, Subnet Mask, Default Gateway, DNS Server, Lease Time, Excluded Address, DHCP Pool, Network Configuration, IP Binding, DHCP Reservation, Dynamic IP, Static IP, Show Commands, Debugging, Packet Tracer, Network Automation, Router Configuration, CCNA, سیسکو

Topology