What protocol uses port 389 for managing user accounts in environments like Microsoft Active Directory?

The Lightweight Directory Access Protocol (LDAP) is the correct answer because it is specifically designed for accessing and managing directory information services over a network. It operates on port 389 by default, making it suitable for applications that involve managing user accounts, groups, and other directory data. In environments like Microsoft Active Directory, LDAP is essential for performing queries and updates related to user accounts and directory structure.

LDAP provides a structured way to access directory services, allowing applications to communicate with directory servers. The protocol supports operations such as authentication, authorization, and retrieval of directory information, which are crucial for user account management in enterprise environments.

In contrast, the other protocols mentioned—Secure Sockets Layer (SSL), File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP)—serve different purposes. SSL is a security protocol that ensures encrypted communication over a network, FTP is primarily used for transferring files between computers, and SMTP is used for sending emails. None of these protocols deal with managing user accounts within directory services, making LDAP the appropriate choice in this context.