⚑ Deus Ex Machina ➽ Eventlog Lookup

Deus Ex Machina » Eventlog » Event 5807 - NETLOGON



Description »
During the past 4.23 hours there have been 13 connections to this Domain Controller from client machines whose IP addresses don't map to any of the existing sites in the enterprise. Those clients, therefore, have undefined sites and may connect to any Domain Controller including those that are in far distant locations from the clients. A client's site is determined by the mapping of its subnet to one of the existing sites. To move the above clients to one of the sites, please consider creating subnet object(s) covering the above IP addresses with mapping to one of the existing sites.  The names and IP addresses of the clients in question have been logged on this computer in the following log file '%SystemRoot%\debug\netlogon.log' and, potentially, in the log file '%SystemRoot%\debug\netlogon.bak' created if the former log becomes full. The log(s) may contain additional unrelated debugging information. To filter out the needed information, please search for lines which contain text 'NO_CLIENT_SITE:'. The first word after this string is the client name and the second word is the client IP address. The maximum size of the log(s) is controlled by the following registry DWORD value 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters\LogFileMaxSize'; the default is 20000000 bytes.  The current maximum size is 20000000 bytes.  To set a different maximum size, create the above registry value and set the desired maximum size in bytes.
Data formatted as » None

This event is logged to tell you that the domain controller is getting requests from IP addresses which are not part of any subnet which is a part of an AD site.
Take a look at the %WINDIR%\debug\netlogon.log file for lines with the string NO_CLIENT_SITE. You should see something like this:

mm/dd hh:mm:ss Domain: Error: Hostname IP-Address
04/01 23:36:32 WINDOMAIN: NO_CLIENT_SITE: HQWS0405
04/02 00:06:55 WINDOMAIN: NO_CLIENT_SITE: HQWS0405
04/04 09:03:01 WINDOMAIN: NO_CLIENT_SITE: HQWS0405
06/29 10:08:10 WINDOMAIN: NO_CLIENT_SITE: MKLP0019
06/29 10:08:10 WINDOMAIN: NO_CLIENT_SITE: MKLP0019

The next step is to work out which AD sites these IP addresses should belong to, and to ensure that you have a matching subnet in that site. Take a special note of the subnet masks, and make sure the definitions include the IP addresses you think they do.

You can add or modify the subnets and sites using the Active Directory Sites and Services mmc snap-in. Generally, you will need to be a Domain Administrator in the forest root domain, or an Enterprise Administrator in order to make such changes.