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 Book is Here... and Now On Sale!

Read offline with no ads or diagram watermarks!
The TCP/IP Guide

Custom Search







Table Of Contents  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

Previous Topic/Section
DHCP Address Assignment and Allocation Mechanisms
Previous Page
Pages in Current Topic/Section
12
3
4
Next Page
DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers
Next Topic/Section

DHCP Leases, Lease Length Policies and Management
(Page 3 of 4)

Common Lease Durations

The administrator need not pick from “short” and “long” lease durations. He or she can “compromise” by choosing a number that best suits the network. Some examples of lease times and the reasoning behind them:

  • One Hour Or Less: Ensures maximum IP address allocation efficiency in a very dynamic environment where there are many devices connecting and disconnecting from the network, and the number of IP addresses is limited.

  • One Day: Suitable for situations where “guest” machines typically stay for a day, to increase IP efficiency when many employees work part-time, or otherwise to ensure that every day each client must ask again for permission to use an address.

  • Three Days: This is the default used by Microsoft. This alone makes it a popular choice.

  • One Week: A reasonable “compromise” between the shorter and longer times.

  • One Month: Another “compromise”, closer to the longer end of the lease time range.

  • Three Months: Provides reasonable IP address stability so that addresses don't change very often in reasonably static environments. Also a good idea if there are many IP addresses available and machines are often turned off for many days or weeks at a time. May be used in a university setting to ensure that IP addresses of returning students are maintained over the summer recess.

  • One Year: An approximation of an “infinite” lease; see below.
Assigning Lease Length By Client Type

In fact, not only is the administrator not restricted to a limited number of possible lease durations, it is not necessary for the administrator to choose a constant lease length policy for all clients. Depending on the capabilities of the DHCP server, an administrator may select different lease lengths for certain clients than others. For example, the administrator may decide to use long leases for desktop computers that are permanently assigned to a particular subnet and not moved, and a pool of short-leased addresses for notebooks and “visitors”. In some DHCP implementations this can be done by assigning clients to particular “classes”. Of course, this requires more work (and may even require multiple servers.)


Previous Topic/Section
DHCP Address Assignment and Allocation Mechanisms
Previous Page
Pages in Current Topic/Section
12
3
4
Next Page
DHCP Lease "Life Cycle" Overview (Allocation, Reallocation, Renewal, Rebinding and Release) and Lease Timers
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.