The Lightweight Directory Access Protocol secured over SSL uses port 636. This implementation ensures that the communication between the client and server is encrypted, which is fundamental for secure data transmission in a corporate environment. It is critical to note that while other directory access and communication protocols exist, such as LDAP over port 389, they do not offer the same level of security as LDAPS, which specifically includes encryption with SSL. Conversely, ports 443 and 993 are typically associated with secure HTTP and IMAP protocols, respectively, not with directory services.