DOCUMENT:Q150828  19-DEC-1999  [exchange]
TITLE   :XFOR: Dirsync Role/Number of Servers can Change DXA Addresses
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0,5.0,5.5
OPER/SYS:
KEYWORDS:kbusage exc4 exc5 exc55

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The information in this article applies to:

 - Microsoft Exchange Server, versions 4.0, 5.0, 5.5 
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SUMMARY
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The Microsoft Exchange Directory Synchronization agent (DXA) can have different
email addresses depending on how many instances of the service exist in a single
site and the role it plays in directory synchronization. This is allowable by
the Microsoft Mail directory synchronization protocol.

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

When you install the first MSMail Connector component in a site, the DXA is
assigned the MSMail alias $SYSTEM. For example:

   First server:  <organization>/<site>/$SYSTEM

When you add additional MSMail Connectors to the site, $SYSTEM is replaced by
SYSTEMx, where x starts with 1 and is incremented by 1 with each additional
MSMail connector installed. For example:

   Second Server: <organization>/<site>/SYSTEM1
   Third Server:  <organization>/<site>/SYSTEM2

However, if Microsoft Exchange Server is a directory synchronization requestor,
the SYSTEMx address will be used, even if this is the first Microsoft Exchange
Server in the site. This is because we don't know if there will be another
Microsoft Exchange Server in the site that will act as a directory
synchronization server, in which case the address must be $SYSTEM.

If a Microsoft Exchange Server that acts as a directory synchronization server is
later changed to be a directory synchronization requestor, the DXA address will
be modified to SYSTEM1. If a SYSTEM1 address already exists in the same site,
SYSTEM2 will be used and so forth.

Additional query words:

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Keywords          : kbusage exc4 exc5 exc55 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbExchange400 kbZNotKeyword2
Version           : winnt:4.0,5.0,5.5

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