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Q195911: XADM: Directory Replication Conflicts and Event ID 1074

Article: Q195911
Product(s): Microsoft Exchange
Version(s): WinNT:5.0,5.5
Operating System(s): 
Keyword(s): 
Last Modified: 25-APR-1999

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The information in this article applies to:

- Microsoft Exchange Server, versions 5.0, 5.5 
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SUMMARY
=======

When you attempt to modify a Directory Object at the same time using multiple
instances of the Exchange Server Administrator program on different servers in
the same site, the user may receive the following Event in the Windows NT
Application log:

  Event Id: 1074
  Source: MSExchangeDS
  Category: Replication
  Type: Warning
  Description:
  Replication warning: There was a conflict with replication.
  Modifications made to object
  /o=Alpha/ou=Omega/cn=Recipients/cn=Technical Disc by directory with
  globally unique identifier (GUID) 74799c39c5b2d11197230001fa6a0863
  EXCHANGE05 were lost.

This event indicates that a directory object was modified on two different
servers in the same site before the change has had chance to be replicated.
Because of this, one server's changes were discarded. Any directory object may
be affected including a mailbox, distribution list, address-book view, or custom
recipients.

You will not see the above Event ID in the log unless the Directory Service's
diagnostic logging has been increased in the following diagnostics logging
category: REPLICATION.

This is not a problem with the Microsoft Exchange Directory. The basic rule to
follow when modifying objects is to make changes to an object from only one
point in a site. If an object is modified on two different servers within the
same site within the directory replication interval, then it is possible for
directory replication conflicts to occur.

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

Microsoft Exchange Server uses the following methodology to handle conflicts
during directory replication. The directory service first checks the
Object-Version of the object when the directory service receives a change.

In most cases, the Object-Version is higher than the existing Object- Version of
the object in the local directory, so the change will be committed to the local
directory. If the Object-Version is lower, then the change is ignored and not
committed to the local directory. If the Object- Version is the same value, then
the directory service compares the existing DSA-Signature of the Object on the
local directory to the incoming object's DSA-Signature. If these DSA-Signatures
match, then the change is committed to the local directory. If the
DSA-Signatures are different, then the Directory service compares the
When-Changed attribute of the Object on the local directory and the When-Changed
attribute of the incoming object change. The Directory service commits to the
local directory the object that has the more recent When-Changed attribute.

The following are examples of activities that can lead to directory replication
conflicts:

- Exchange Administrators modifying any object from more than one server at the
  same time.

- Running the Microsoft Mail migration from more than one server or workstation
  that is migrating msmail users to the same Exchange Server site. The
  conflicts will occur in this scenario if the msmail custom recipients are
  members of Exchange Server distribution lists that will be updated
  simultaneously by the computers performing the migration. In this scenario,
  the distribution lists' memberships may contain unknown objects that have
  gear icons associated with them. (Similar looking to Free Busy Agent Icon.)

Additional query words: msmail migration 1074 directory replication conflict distribution lists

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Keywords          :  
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbZNotKeyword2
Version           : WinNT:5.0,5.5
Issue type        : kbinfo

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