Changing the Weight and Priority of a Domain Controller Within a Site

Paul Bergson — Fri, 09 Jul 2010 05:37:00 GMT

If you have multiple domain controllers (dc) within a site and you would like to have one of these dc's refered to more often or only if no other dc is available. Selection of a dc within a site is controlled by both the weight and priority.

Weight of a Domain Controller

By default all dc's have a weight of 100, the heavier the weight the more often the dc is referred to. The formula for the referral is based is an elementary math. If there are two servers in a site and one has a weight of 100 and the other 200. The dc with twice the weight will receieve twice the referals.

To modify the weight of a dc the registry key:

HKLM\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters\LdapSrvWeight is used.

Priority of a Domain Controller

By default all dc's have a priority of 0, the lower the priority the first in priority. The dc with the lowest priority in the site will receive ALL authentication requests unless it is unavailable. If the lowest priority dc is unavailable then the next lowest dc in the site will receive all requests, etc...

To modify the priority of a dc the registry key:

HKLM\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters\LdapSrvPriority is used.

For additional information see: http://technet.microsoft.com/en-us/library/cc787370(WS.10).aspx

Paul Bergson (MVP - Directory Services) : Weight

Changing the Weight and Priority of a Domain Controller Within a Site