...
Connection Encryption with LDAPS
LDAPS is a the non-official standardized "LDAP over SSL" protocol that in contrast with StartTLS only allows communication over a secure port such as 636. It establishes the secure connection before there is any communication with the LDAP server. LDAPS generally provides protection against man-in-the-middle attacks and a higher level of security than StartTLS as it explicitly does not allow insecure LDAP connections.
...