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Introduction to DHCP (Dynamic Host Configuration Protocol)

CCNA: 0 to Hero - Comprehensive Network Engineering Bootcamp

Lesson 42: Introduction to DHCP

Dynamic Host Configuration Protocol (DHCP) automates the assignment of IP address configuration (IP address, subnet mask, default gateway, DNS server) to client devices.

The DORA Process

DHCP operates using four primary steps:

  1. Discover: The client broadcasts a DHCP Discover message (looking for a server).
  2. Offer: The DHCP server responds with a DHCP Offer (proposing an IP address and configuration).
  3. Request: The client broadcasts a DHCP Request (accepting the offer).
  4. Acknowledge (ACK): The server sends a DHCP ACK (final confirmation and lease agreement).

DHCP Components

  • DHCP Server: The device holding the IP pool and configuration details.
  • DHCP Client: The device requesting the address.
  • DHCP Relay Agent: Typically a router or Layer 3 switch that forwards broadcast Discover messages across network boundaries to reach a remote DHCP server.