What is the default port for LDAP?

The default port for LDAP (Lightweight Directory Access Protocol) is 389. This port is used for unsecured communication between LDAP clients and servers. LDAP is a protocol for accessing and maintaining distributed directory information services over an IP network, commonly used for storing and retrieving user information in an Active Directory or similar systems.

Using port 389 allows applications to perform a variety of directory-related functions, such as querying for user data, authentication, and updating directory entries. While option 636 refers to LDAP over SSL (LDAPS), which is a secure LDAP connection, it is not the default port. Ports 80 and 21 are used for HTTP and FTP respectively and are not associated with LDAP at all. Thus, 389 stands out as the correct default port for general LDAP communications.