Obtaining a Link ID

Starting with Windows Server 2003, it is no longer necessary to request a linkID from Microsoft; there is a process for automatically generating a linkID. The system will automatically generate a link ID for a new linked attribute when the attribute's linkID attribute is set to 1.2.840.113556.1.2.50. A back link for this forward link is created by setting the linkID to the attributeID or ldapDisplayName of the forward link. The schema cache must be reloaded after creating the forward link and before creating the back link. Otherwise, the forward link's attributeId or ldapDisplayName will not be found when the back link is created. The schema cache is reloaded on demand, a few minutes after a schema change is made, or when the DC is restarted. Create all forward links, reload the schema cache and then create all back links.

For example, when you have created the new attributes myForwardLinkAttr and myBackLinkAttr, and wish to link them:


The OIDs in this example are contrived. See Obtaining an Object Identifier from Microsoft for instructions on obtaining OIDs for new attributes.


  1. Set these attributes on the attribute that is to be the forward link:

    ldapDisplayName: myForwardLinkAttr
    OID: 1.2.840.113556.6.1234
    LinkID: 1.2.840.113556.1.2.50
  2. Reload the Schema.

  3. Set these attributes on the attribute that is to be the back link:

    ldapDisplayName: myBackLinkAttr
    OID: 1.2.840.113556.6.1235
    LinkID: 1.2.840.113556.6.1234 or myForwardLinkAttr

Linked Attributes

How to Extend the Schema