Microsoft KB Archive/253832

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Knowledge Base

XADM: Description of the Active Directory Connector Schema Map

Article ID: 253832

Article Last Modified on 1/27/2007


  • Microsoft Exchange 2000 Server Standard Edition
  • Microsoft Exchange Server 5.5 Service Pack 3
  • Microsoft Windows 2000 Standard Edition

This article was previously published under Q253832


This article provides a general description of how the Active Directory Connector (ADC) maps attributes by reading a set of rules that are located in the Active Directory. This is the most important job of the ADC.

The ADC replicates entries from the Exchange directory to the Active Directory, replicates entries from the Active Directory to the Exchange directory, and keeps all of these entries synchronized. An entry is a collection of attributes; the ADC maps these attributes from one directory to another.


When you install an ADC for the first time in a forest, the ADC creates an entry in the Configuration container named Default ADC Policy. This entry contains basic rules that apply to all of the Connection Agreements that are created. One of these rules is the schema map that defines the way that attributes are mapped.

These rules are stored in two attributes: the msExchServer1SchemaMap attribute stores rules to map from Active Directory to Exchange, and the msExchServer2SchemaMap attribute stores rules to map from Exchange to the Active Directory.

These two attributes contain information that enables the mapping of other attributes based on attribute name, attribute syntax, and object class. Some attributes have the same name in both directories, such as the mail attribute, and some attributes have different names. For example, the homeMDB attribute in the Active Directory and the home-MDB attribute in the Exchange directory have names that only differ by a dash, but other attribute names are very different, such as the proxyAddresses attribute in the Active Directory and the otherMailbox attribute in Exchange. The ADC can map these attributes in a simple manner because it matches the attribute names to each other.

Attributes that have different syntax or different sizes pose the greatest challenge. The ADC must replicate back and forth and not lose the information. Attributes such as the manager attribute or the member attribute also pose a challenge, because they are not simple string values, but links to another object. In this case, the ADC must resolve the link before it can replicate the entry. If the link is not present, it is retried after a specified interval.

To control the schema map:

  1. Open the Active Directory Connector snap-in in Microsoft Management Console (MMC).
  2. Right-click Active Directory Connector Management, and then click Properties in the shortcut menu.
  3. There are two tabs available: the From Exchange tab and the From Windows tab. Click one of these tabs, as applicable. On these tabs, if you click to select the check box next to an attribute, you enable replication for that attribute, and if you click to clear the check box next to an attribute, you disable replication for that attribute.

NOTE: Use caution when you disable the replication of some attributes, because you may disrupt the ADC.

Keywords: kbinfo KB253832