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)                      9  DHCP Address Assignment and Dynamic Address Allocation and Management

DHCP Address Assignment and Allocation Mechanisms 1 2 3 4 DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers

Of the three address allocation methods supported by DHCP, dynamic address allocation is by far the most popular and important. The significance of the change that dynamic addressing represents to how IP addresses are used in TCP/IP can be seen in the semantics of how addresses are treated in DHCP. Where conventionally a host was said to own an IP address, when dynamic address allocation is used, hosts are said instead to lease an address.

The notion of a “lease” conveys very accurately the difference between dynamic allocation and the other types. A host no longer is strictly “entitled” to a particular address, with a server merely telling it what the address is. In DHCP, the server remains the real owner of all the IP addresses in the address pool, and merely gives permission for a client to use the address for a period of time. The server guarantees that it will not try to use the address for another client only during this time. The client is responsible for taking certain actions, as we will see later in this section, if it wants to continue using the address. If it does not successfully reacquire permission for using the address after a period of time, it must stop using it, or risk creating an IP address conflict on the network.

DHCP Address Assignment and Allocation Mechanisms 1 2 3 4 DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers