Some DNS queries fail on Windows Server 2008 R2

Last Review: August 7, 2010
Product(s): Windows Server 2008 R2

After you deploy a Windows Server 2008 R2-based DNS server, DNS queries to some domains may not be resolved successfully. This issue occurs because of the Extension Mechanisms for DNS (EDNS0) functionality that is supported in Windows Server 2003 DNS. 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 following is the workaround.

At a command prompt, type the following command, and then press ENTER:

     dnscmd /config /enableednsprobes 0

Note, type a 0 (zero) and not the letter "O" after "enableednsprobes" in this command.