One of our SBS 2003 boxes started throwing a series of Event ID 4521 errors in the DNS log on a very regular basis:
SBS 2003 – DNS Event ID 4521
The error was:
Event Type: Warning
Event Source: DNS
Event Category: None
Event ID: 4521
Time: 2:34:34 PM
The DNS server encountered error 9002 attempting to load zone . from Active Directory. The DNS server will attempt to load this zone again on the next timeout cycle. This can be caused by high Active Directory load and may be a transient condition.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
The fix for the problem was actually quite simple. At the command line run the following:
- dnscmd /config /BootMethod [Enter]
After recycling the DNS Server service, the errors, as shown in the above screenshot, stopped happening.
Thanks to Robert Premuz for the solution at the bottom of the forum post here: TechArena: DNS Event 4521 after SP2 on SBS 2003 Std.
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book