An LDAP alias is an LDAP entry that contains the distinguished name of another LDAP entry on the same LDAP server. LDAP servers are responsible for dereferencing aliases. A link reference differs from an alias in that it is not LDAP-specific and can name objects outside of the LDAP namespace or server. An LDAP referral is an LDAP entry that contains the URL of another LDAP entry, possibly on another LDAP server. The URL need not be an LDAP URL, but the entry it names must be an LDAP entry.
LDAP clients are responsible for dereferencing referrals.
A link reference differs from a referral in that it is not LDAP-specific. It need not name another LDAP entry. A UNIX symbolic link contains a relative or absolute name of a file or directory. It differs from a link reference in that it can name only another file or directory. A link reference differs from a URL reference in that it is explicitly typed and designed to support links, whereas a URL reference is intended primarily to support federation.