Schema 1

In Schema 1, the inetCanonicalDomainName attribute is used for the same purpose as in Schema 2, but it is used with DC nodes in the DC tree.

This attribute is used when more than one DC node in a DC tree refers to the same base node of a user/group tree for a particular domain in the Organization tree. (There can be only one canonical domain name for a domain's user/group base node in the Organization tree, but there can be many DC nodes referring to the same user/group base node.)

In Schema 1, this attribute is not necessary if there is only one DC node referring to a domain's user/group base node. If the attribute is missing, the DC node entry is taken for the canonical domain name.

If this attribute is missing and there are multiple DC nodes referring to the same user/group base node, the mail processes could possibly use the wrong domain name when trying to open users’ mailboxes.

Using multiple domain nodes to point to the same user/group base node allows you to have different attribute settings (for example, to achieve different routing) for each one. If you want to be sure the two domains have the same attribute settings (for example, to ensure that they are routed identically), use aliasedObjectName on the duplicate node instead.