IP Address Assignment and Fetch Protocols

These protocols handle the assignment and retrieval of IP addresses in networks, enabling devices to configure their network interfaces dynamically or statically.

Protocol

Description

Use Case

APIPA (Automatic Private IP Addressing)

Automatically assigns an IP address from the 169.254.0.0/16 range when DHCP servers are unavailable. Allows basic local network communication without manual configuration.

Small or isolated networks with no DHCP server.

BOOTP (Bootstrap Protocol)

Predecessor to DHCP that assigns IP addresses and bootstraps diskless clients by providing boot image info. Uses UDP and broadcasts requests on network.

Diskless workstations and early IP address assignment.

DHCPv4 (Dynamic Host Configuration Protocol for IPv4)

Automatically assigns IPv4 addresses and network configuration parameters to devices. Supports leasing, renewal, and various options for flexible network setup.

Most common protocol for IPv4 address assignment in LANs.

DHCPv6 (Dynamic Host Configuration Protocol for IPv6)

Extends DHCP functionality to IPv6 networks for dynamic IPv6 address assignment and configuration. Supports stateful and stateless address configurations.

IPv6 network address management.

RARP (Reverse Address Resolution Protocol)

Maps MAC hardware addresses to IP addresses. Used by diskless clients to obtain their IP addresses from a server.

Legacy systems and early IP assignment before DHCP.

RFC: Defined in Microsoft documentation (not standardized by IETF)

Main Features:

  • Assigns IP addresses from the 169.254.0.0/16 range when no DHCP server is available

  • Requires no manual configuration or external server

  • Enables local communication between devices on the same subnet

  • Used by Windows and some other systems as a fallback mechanism

  • No default gateway or DNS support

Use Cases:

  • Small or isolated local networks with no DHCP infrastructure

  • Quick device-to-device communication without administrator intervention

  • Troubleshooting DHCP failures

Alternative Protocols:

  • DHCPv4 – Standard dynamic IP address assignment

  • Static IP configuration – Manual assignment

  • Zeroconf/Bonjour – Includes APIPA-like addressing with service discovery

Let us learn more about APIPA:

Jump to “APIPA”

RFC: RFC 951, RFC 1048 (Vendor extensions)

Main Features:

  • Assigns IP addresses to clients via UDP

  • Originally designed for diskless clients to obtain boot image paths

  • Provides static mappings via configuration files on BOOTP servers

  • Stateless, no lease mechanism (unlike DHCP)

  • Broadcast-based request mechanism

Use Cases:

  • Bootstrapping diskless workstations and network appliances

  • Early network installations before DHCP became standard

  • Environments requiring deterministic IP assignment

Alternative Protocols:

  • DHCP – More flexible successor with leasing and dynamic config

  • PXE – For network booting with DHCP/BOOTP support

  • Static IP configuration – Manual alternative for bootstrapping

Let us learn more about BOOTP:

RFC: RFC 2131

Main Features:

  • Automatically assigns IPv4 addresses and config parameters

  • Uses leasing system with renewals and expirations

  • Supports DNS, gateway, subnet mask, and other options

  • Reduces administrative burden in large networks

  • Works over UDP ports 67 (server) and 68 (client)

Use Cases:

  • IPv4 address assignment in home and enterprise LANs

  • Wireless network configuration

  • Guest Wi-Fi networks with short-term leases

  • Large-scale deployments needing automated IP provisioning

Alternative Protocols:

  • Static IP assignment – Manual configuration

  • BOOTP – Legacy method, lacks dynamic features

  • APIPA – Fallback mechanism when DHCP fails

Let us learn more about DHCPv4:

Jump to “DHCPv4”

RFC: RFC 8415 (latest core spec)

Main Features:

  • Provides dynamic address assignment for IPv6 networks

  • Supports stateful and stateless configuration modes

  • Works with Router Advertisements (RA) for hybrid deployments

  • Can deliver DNS, NTP, domain search options, etc.

  • Operates over UDP port 546 (client) and 547 (server)

Use Cases:

  • IPv6-enabled enterprise and ISP networks

  • Hybrid IPv6 deployments with RA + DHCPv6

  • Devices requiring detailed config beyond SLAAC

  • Centralized address tracking and logging

Alternative Protocols:

  • SLAAC (Stateless Address Autoconfiguration) – Lightweight alternative

  • Static IPv6 addressing – Manual configuration

  • ND (Neighbor Discovery) – Provides link-layer info, complements DHCPv6

Let us learn more about DHCPv6:

Jump to “DHCPv6”

RFC: RFC 903

Main Features:

  • Legacy protocol to map MAC addresses to IP addresses

  • Used by diskless clients to determine their IP at boot time

  • Operates at Layer 2 using Ethernet frames (not IP)

  • Requires a RARP server on the local network

  • Limited scalability and features compared to DHCP

Use Cases:

  • Bootstrapping early Unix-based systems or embedded devices

  • Static IP assignment to known MAC addresses

  • Legacy network boot environments

Alternative Protocols:

  • BOOTP – Adds boot file support and UDP/IP transport

  • DHCP – Offers dynamic leases, multiple config options

  • Static configuration – For fixed IP needs in modern systems

Let us learn more about RARP:

Jump to “RARP”