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 Dynamic Address Allocation and Management 1 2 3 4 DHCP Leases, Lease Length Policies and Management

Automatic Allocation

The third option, automatic allocation, can be used in cases where there are enough IP addresses for each device that may connect to the network, but where devices don't really care what IP address they use. Once an address is assigned to a client, that device will keep using it. Automatic allocation can be considered a “special case” of dynamic allocation: it is essentially dynamic allocation where the time limit on the use of the IP address by a client (the lease length) is “forever”.

In practice, automatic allocation is not used nearly as much as dynamic allocation, for a simple reason: automatically assigning an IP address to a device permanently is a risky move. Most administrators feel it is better to use manual allocation for the limited number of machines that really need a permanent IP address assignment, and dynamic addressing for others. We'll discuss this more in the next topic.

DHCP Address Assignment and Dynamic Address Allocation and Management 1 2 3 4 DHCP Leases, Lease Length Policies and Management