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Q224460: Err Msg: Error Connecting to <Servername> The RPC Service…

Article: Q224460
Product(s): Internet Information Server
Version(s): 4.0
Operating System(s): 
Keyword(s): kbWinNT400sp4fix
Last Modified: 11-JUN-2002

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The information in this article applies to:

- Microsoft Internet Information Server version 4.0 
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IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

  Q256986 Description of the Microsoft Windows Registry

SYMPTOMS
========

When you attempt to remotely administer a multihomed IIS 4.0 computer from the
Microsoft Management Console (MMC) on a local computer, the following error
messages may occur:

  Error connecting to <servername> The RPC service is not available

When you click OK, you may see a few additional errors similar to the following:

  Unable to administer IIS "unable to connect to target machine"

CAUSE
=====

This problem only occurs when you are trying to remotely administer a multihomed
IIS 4.0 computer from the MMC on a local computer. The MMC uses the default DCOM
protocol for remote communications. By default, DCOM uses the ncadg_ip_udp DCOM
protocol for connections instead of ncacn_ip_tcp. Due to a problem with the
ncadg_ip_udp DCOM protocol in Windows NT Service Pack 3, if the destination IIS
computer is multihomed, ncadg_ip_udp causes the binding IP address to become
corrupted.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Windows NT version
4.0. For additional information, please see the following article(s) in the
Microsoft Knowledge Base:

  Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack


WORKAROUND
==========

If you have not yet implemented Windows NT Service Pack 4 in your environment,
you can edit the registry to change the DCOM protocols that are used.

WARNING: If you use Registry Editor incorrectly, you may cause serious problems
that may require you to reinstall your operating system. Microsoft cannot
guarantee that you can solve problems that result from using Registry Editor
incorrectly. Use Registry Editor at your own risk.
Follow these steps exactly on the multihomed remote Web server:

1. Back up the following registry key using Regedt32.exe (not Regedit.exe):

  HKEY_Local_Machine\Software\Microsoft\RPC

  To do this, highlight the RPC key and choose Registry, and the choose Save
  Key.

2. In the RPC key, edit the DCOM Protocols setting by double-clicking on it.
  Change the values to reflect a different order by removing the ncadg_ip_udp
  protocol and moving ncacn_ip_tcp to the top of the list. Here is what it will
  look like before and after the change:

  Before

  ncadg_ip_udp
  ncadg_ipx
  ncacn_ip_tcp
  ncacn_spx
  ncacn_nb_nb
  ncacn_nb_ipx

  Remove ncadg_ip_udp and move ncacn_ip_tcp to the top of the list.

  After

  ncacn_ip_tcp
  ncadg_ipx
  ncacn_spx
  ncacn_nb_nb
  ncacn_nb_ipx

3. After the changes are made, close Registry Editor and restart the computer.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 4.0. This
problem was first corrected in Windows NT 4.0 Service Pack 4.

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

For additional information about network connection delays, click the article
number below to view the article in the Microsoft Knowledge Base:

  Q288886 PRB: Delayed DCOM Activation on Multihomed Computers

Below is an example of how the binding fails.

Note: Binding Vector[4] has the incorrect IP addresses in the binding handle. In
this example, it combines both IP addresses from both NICs, thus corrupting the
IP address format, and the connection fails.

Display STRING representation for each binding handle in Binding Vector

  Binding Handle Count: 7
  Binding Vector[0]: ncacn_np:\\\\ServerName[\\pipe\\000000B4.001]
  Binding Vector[1]: ncalrpc:ServerName[WMSG000000B4.00000001]
  Binding Vector[2]: ncacn_ip_tcp:157.61.239.61[1038]
  Binding Vector[3]: ncacn_ip_tcp:157.61.239.5[1038]
  Binding Vector[4]: ncadg_ip_udp:157.61.239.61157.61.239.5[1039]
  Binding Vector[5]: ncadg_ip_udp:157.61.239.5[1039]
  Binding Vector[6]: ncacn_nb_tcp:ServerName[106]

If you use network sniffers, such as Network Monitor, you can see the incorrect
IP addresses as in the above example for Binding Vector[4].

Additional query words: mmc, ntop, iis, dcom, rpc, multi-homed, multi, homed sp hot fix qfe

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Keywords          : kbWinNT400sp4fix 
Technology        : kbiisSearch kbiis400
Version           : :4.0
Issue type        : kbbug
Solution Type     : kbfix

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