Revision Note: Advisory published.Summary: Microsoft is announcing the availability of an update to DNS devolution that can help customers in keeping their systems protected. Customers whose domain name has three or more labels , such as "contoso.co.us", or who do not have a DNS suffix list configured, or for whom the following mitigating factors do not apply may inadvertently be allowing client systems to treat systems outside of the organizational boundary as though they were internal to the organization's boundary.

Read more at: http://www.microsoft.com/technet/security/bulletin/MSpx?pubDate=2009-06-09