Some DNS name queries are unsuccessful after upgrade to Windows Server 2008 R2

by Thomas Forsmark Sørensen 13. October 2010 11:13

I have seen problems resolving some DNS names at several of our customers after upgrading their DNS servers to Windows Server 2008 R2.

It happens to be a known problem with the "Extension Mechanisms for DNS (EDNS0)" functionality of DNS in Windows Server 2008 R2 and some firewalls.

ENDS0 permits the use of larger User Datagram Protocol (UDP) packet sizes. However, some firewall programs may not permit UDP packets that are larger than 512 bytes. As a result, these DNS packets may be blocked by the firewall.

The resolution to the problem is to run the following command on every Windows Server 2008 R2 DNS server.

dnscmd /config /enableednsprobes 0

Further information can be found in this KB article:

How to recreate an accidentally deleted AD integrated DNS zone.

by Thomas Forsmark Sørensen 5. May 2010 21:01
Some time ago I had a serious problem at a costumer.
The customer had two AD domains in the same Forrest. One of them was running Windows Server 2008 R2 and the other Windows Server 2003 R2.
In the 2003 domain i went into the DNS console and changed the DNS zone replication from "To all DNS servers running on domain controllers in this domain" to "To all DNS servers running on domain controllers in this Forrest".
After a while I saw that the DNS zone for the domain on the 2003 server was missing.... Frown
I looked in the event log and found the following event: More...

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About Me


My name is Thomas Forsmark Sørensen.

I live in Odense in Denmark and work for Globeteam in Virum.

I am working as a Microsoft Infrastructure consultant with main focus on application and Operating System Deployment.

I work mostly with Microsoft System Center Configuration Manager 2012 R2 and MDT 2013, but I also work with other of Microsofts products. 


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