LDAP servers can be configured to use as authenticator in Weblogic Server. In order to efficiently use an LDAP server, it must be possible to uniquely identify LDAP objects. GUID attributes can be considered a unique identifier for an LDAP object. There are several specific and some more generic LDAP authentication providers available for Weblogic Server. The specific authentication providers have default GUID (global universal identifier) attributes (see here at 'Use of GUID and LDAP DN Data in WebLogic Principals'). When using the generic Weblogic Server LDAPAuthenticator, there is no default GUID attribute. In order for LDAP caching to work and to allow browsing of group memberships for users, the GUID attribute needs to be defined. The entryUUID is a good candidate for this since every LDAP server should support it. See RFC 4530. Also see here.