When assigned to the ref attribute for ou=people,dc=example,dc=com, which of the following values will create a subordinate knowledge link to slave.example.com?

The correct syntax for an LDAP URL used in a 'ref' attribute (referral) is ldap://<hostname>:<port>/<baseDN>. Option A, ldap://slave.example.com/ou=people,dc=example,dc=com, correctly specifies the protocol, the target server slave.example.com, and the base Distinguished Name (DN) /ou=people,dc=example,dc=com for the referred subtree, thus forming a valid subordinate knowledge link.

The '?' character in an LDAP URL typically separates the DN from attributes to return or search scope, not the hostname from the base DN for a referral.

Using a space between the hostname and the base DN is not a valid LDAP URL syntax.

Using a comma between the hostname and the base DN is not a valid LDAP URL syntax.