Final answer:
IMAP, FTPS, and SFTP exclusively utilize TCP ports for their operations and do not make use of UDP. These protocols rely on TCP for a reliable connection-oriented service.
Step-by-step explanation:
A student has inquired about which of the listed services uses only TCP ports and not UDP. To answer this question, it is important to understand that certain internet services run exclusively over the TCP protocol because it provides a reliable connection-oriented service. Here is the breakdown of the services mentioned:
- IMAP (Internet Message Access Protocol) - Primarily uses TCP port 143 for unencrypted connections or port 993 for TLS/SSL encrypted connections. IMAP does not use UDP for its operations.
- LDAP (Lightweight Directory Access Protocol) - Commonly runs over TCP port 389. Although it can also run over UDP on the same port for connectionless operations, LDAP is typically known for its TCP implementation.
- FTPS (File Transfer Protocol Secure) - An extension of FTP, which uses TCP ports 20 and 21 for command and data transfer, with added layers of security like SSL/TLS. FTPS does not utilize UDP.
- SFTP (SSH File Transfer Protocol) - Uses TCP port 22, which is the same port as SSH (Secure Shell), for secure file transfer and does not operate over UDP.
Given the options, IMAP, FTPS, and SFTP are the services that exclusively use TCP without relying on UDP.