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If all users reside under the same single-depth container object (e.g., CN=Users,DC=example,DC=edu), the standard ports can likely be used:
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If users are spread across multiple containers object (e.g., CN=Staff,DC=example,DC=edu and CN=Faculty,DC=example,DC=edu) or if the standard connection method (above) doesn't work, the global catalog ports can be used:
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As a general note, the global catalog supports searches across the entire forest. Attributes that are to should be released accessible to the CAS server Shibboleth IdP will have to be specified as part of the Partial Attribute Set (PAS) in Active Directory.
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