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 format for an LDAP URL that specifies a base DN on a particular host is `ldap://hostname/dn`. Therefore, `ldap://slave.example.com/ou=people,dc=example,dc=com` correctly forms a subordinate knowledge link, directing clients to the specified DN on `slave.example.com` for that subtree.

The question mark (?) in an LDAP URL is used to separate the base DN from attribute lists, scope, or filters, not to append the DN itself.

An LDAP URL does not use a space to separate the hostname from the distinguished name, making this an invalid URL format.

A comma (,) is used within the components of a distinguished name, not as a separator between the hostname and the DN in an LDAP URL.