DOCUMENT:Q159299  10-APR-1999  [exchange]
TITLE   :XFOR: IMC Unable to Resolve Host Addr. Using Raptor Firewall
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:kbusage

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The information in this article applies to:

 - Microsoft Exchange Server, version 4.0 
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SYMPTOMS
========

When using Raptor Firewall DNS proxy caching, and trying to send mail to a host
where the Mail domain is the same as the Address Record domain, the IMC cannot
resolve the Fully Qualified Domain Name (FQDN) to an IP address. For example,
the Address (A) record and Mail Exchanger (MX) record in the DNS may look like
the following:

   microsoft.com.  IN  A  123.123.123.123
   microsoft.com.  IN  MX  10  microsoft.com.

CAUSE
=====

The IMC buffer that holds the DNS response incorrectly assesses the end of the
buffer. If there are no additional resource records, this causes the IMC to fail
during host resolution.


WORKAROUND
==========

Change the mail domain so that it is different from the mail exchanger host.
This means the SMTP address used by your Microsoft Exchange Server users will
also change.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 4.0. This problem was corrected in the latest Microsoft Exchange 4.0
U.S. Service Pack. For information on obtaining the service pack, query on the
following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K


Additional query words:

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Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange400 kbZNotKeyword2
Version           : winnt:4.0
Issue type        : kbbug
Solution Type     : kbfix

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