Microsoft KB Archive/829722

= Mail delivery is slow in Exchange 2000 when the primary DNS server is not available =

Article ID: 829722

Article Last Modified on 10/27/2006

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APPLIES TO


 * Microsoft Exchange 2000 Server Standard Edition

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SUMMARY
In Microsoft Exchange 2000 Server, message delivery to external recipients may be slower than expected when the primary DNS server is not available.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Exchange 2000 Server service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

File information
The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version            Size    File name --  19-Jun-2003  20:05  5.0.2195.6654     322,320  Aqueue.dll 19-Jun-2003 20:05  5.0.2195.6666      67,344  Mailmsg.dll 19-Jun-2003 20:05  5.0.2195.6662      38,672  Ntfsdrv.dll 18-May-2004 16:46  5.0.2195.6920     445,200  Smtpsvc.dll



MORE INFORMATION
By using Microsoft Network Monitor, you can determine the cause of the slower-than-expected mail delivery. You may find that mail delivery performance is affected by DNS query responses, as in the following situation:
 * 1) An initial query is made to the DNS server that is unavailable four seconds after Exchange 2000 sends the message.
 * 2) The query times out after three seconds, and then an additional query is made to the same server.
 * 3) The second query times out after six seconds, and then another query is made to the same server.
 * 4) This final query times out after 12 seconds. Exchange 2000 then forwards the request to the secondary DNS server. The secondary DNS server returns the response, and the message is delivered.

This process takes 25 seconds. Because the DNS responses are not cached, the whole process is repeated for each message that is sent through Exchange 2000. Therefore, mail delivery to external recipients is slower than expected.



STATUS
Microsoft has confirmed that this is a bug in Exchange 2000.

Additional query words: XADM

Keywords: kbhotfixserver kbqfe kbinfo KB829722

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