What Is DHCP – Overview of IP Address Assignment

Understand how the Dynamic Host Configuration Protocol (DHCP) automatically assigns IP settings to devices on a network.

DHCP Overview

The Dynamic Host Configuration Protocol (DHCP) is responsible for automatically assigning IP addresses and related settings to clients on a network. Instead of manually configuring each device, administrators define address scopes, lease durations, and options on a DHCP server.

When a device connects, it requests an address from the DHCP server, which responds with an available IP, subnet mask, gateway, and DNS servers. This streamlines onboarding and reduces configuration errors.

How the DHCP Lease Process Works

A typical DHCP exchange follows a four-step process often remembered as DORA: Discover, Offer, Request, and Acknowledge. The client broadcasts a Discover message, servers reply with Offers, the client Requests one of them, and the chosen server sends an Acknowledge confirming the lease.

Leases have expiration times. Before a lease expires, clients attempt to renew it, allowing them to keep the same address while remaining connected. If renewal fails, the address may be released and assigned to another device.

Command examples
Windows — Inspect and renew DHCP leases

Use these commands in an elevated Command Prompt if needed. 

ipconfig /all        # View current DHCP-assigned settings
ipconfig /release    # Drop current lease
ipconfig /renew      # Request a new lease
macOS — Renew DHCP on common interfaces

Replace en0 with the correct interface name if needed. 

ipconfig getifaddr en0            # Show current IP on Wi‑Fi
sudo ipconfig set en0 DHCP        # Force a new DHCP request

Reservations, Split Scopes, and High Availability

DHCP reservations bind specific MAC addresses to fixed IPs, providing the benefits of static addressing without manual configuration on each client. This is useful for printers, servers, and network appliances.

Larger environments may use split scopes or multiple DHCP servers for redundancy and load distribution. Proper design ensures that address pools do not overlap and that clients can still obtain leases if one server fails.