Please Whitelist This Site? I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :) If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads. If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK. Thanks for your understanding! Sincerely, Charles Kozierok Author and Publisher, The TCP/IP Guide

NOTE: Using software to mass-download the site degrades the server and is prohibited. If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)            9  Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP)                 9  TCP/IP Dynamic Host Configuration Protocol (DHCP)

DHCP Overview, Motivation, History and Standards 1 DHCP Address Assignment and Allocation Mechanisms

The Dynamic Host Configuration Protocol (DHCP) was created as an extension of the older Boot Protocol (BOOTP). The first word in “DHCP” describes the most important new capability that was added to BOOTP: the ability to assign IP addresses dynamically. Moving from a static to a dynamic address allocation model dramatically changes the way we deal with IP addresses in DHCP. Host configuration is transformed from a simple way to tell a host what its address and other parameters are, to a complete tool for managing IP addresses in an organization.

In this section I begin my detailed look at DHCP by describing the concepts behind DHCP address assignment and leases. I begin with a look at how DCHP address assignment works, and a description of the three DHCP address allocation mechanisms. I then delve into DHCP leases and the policies and techniques used to decide how to implement DHCP leasing. I provide an overview of the lease “life cycle” from start to finish, and describe the two DHCP lease timers that help control the process. Finally, I describe DHCP lease address pools and ranges and the general concepts behind address management.

DHCP Overview, Motivation, History and Standards 1 DHCP Address Assignment and Allocation Mechanisms