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Q170059: MS DNS Resolvers’ Behavior with Non-Microsoft Multihomed DNS

Article: Q170059
Product(s): Microsoft Windows NT
Version(s): WinNT:3.51;Windows:95
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 09-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation version 3.51 
- Microsoft Windows NT Server version 3.51 
- Microsoft Windows 95 
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SYMPTOMS
========

This article discusses inconsistent behavior of Windows NT and Windows 95 Domain
Name Service (DNS) resolvers with non-Microsoft multihomed DNS servers, when
these name servers send their responses from addresses different from the one
used to receive the query. This behavior is described below:

With Windows NT 4.0, if the DNS server responds to a query with a different
source IP address than the one the request was sent to, Windows NT 4.0 accepts
the response and continues.

With Windows NT 3.51 or Windows 95, if the DNS server responds to a query with a
different source IP address than the one the request was sent to, Windows NT
3.51 or Windows 95 does NOT accept the response. If only one (primary) DNS
server is listed, the client receives a "Bad IP Address" error message.

If a secondary DNS server is listed and responds to a query with a different
source IP address than the one the request was sent to, Windows NT 3.51 or
Windows 95 accepts the response, no matter what the source IP address of the
response is, and continues.

NOTE: Windows NT 4.0 DNS servers respond to queries with the same source IP
address that the request was sent to.

MORE INFORMATION
================

RFC1035 states:

7.3. Processing responses

  - Some name servers send their responses from different addresses than the
  one used to receive the query. That is, a resolver cannot rely that a
  response will come from the same address which it sent the corresponding
  query to. This name server bug is typically encountered in UNIX systems.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 3.51 and
Windows 95. We are researching this problem and will post new information here
in the Microsoft Knowledge Base as it becomes available.
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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNT351search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS351 kbWinNTS351search kbWin95search kbZNotKeyword3
Version           : WinNT:3.51;Windows:95
Issue type        : kbbug

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