After you install Microsoft Office Communicator 2007 R2 on your computer, you start Office Communicator 2007 R2. The username is preconfigured as <someone>@<domain name>. For example, userA@example.com.When you click the Sign In button to log on to Office Communicator 2007 R2, the example.com domain name is queried. This causes additional traffic on the network.
This problem occurs because Office Communicator 2007 R2 continues to query the domain name every 30 minutes after you click the Sign In button.
To resolve this problem, install the following update rollup:
2028888 Description of the cumulative update package for Communicator 2007 R2: July 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.