Transport protocols: Which file transfer protocol operates over UDP (User Datagram Protocol) rather than TCP?

Introduction / Context:
Understanding which application protocols use TCP versus UDP is essential for firewall rules, performance tuning, and troubleshooting. File transfer protocols vary in complexity, reliability mechanisms, and transport choice, affecting how they behave on lossy or high-latency networks.

Given Data / Assumptions:

• We compare several well-known protocols used for remote access and file movement.
• UDP is connectionless and relies on the application for reliability, if needed.
• TCP provides connection-oriented delivery with congestion control and retransmission.

Concept / Approach:
TFTP (Trivial File Transfer Protocol) uses UDP (commonly port 69) with a simple lock-step request/acknowledgment mechanism at the application layer. In contrast, FTP and Telnet run over TCP. NFS historically used multiple transports depending on version/configuration, but classic TFTP is the canonical UDP-based file transfer protocol in basic networking curricula.

Step-by-Step Solution:

Verification / Alternative check:
Packet captures of a TFTP transfer show UDP datagrams with short data blocks and acknowledgments, rather than TCP segments with sequence/ack windows.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming all file transfers require TCP; forgetting TFTP’s simplicity and use in PXE/bootstrapping scenarios.

Final Answer:
TFTP.