Which statement best distinguishes connectionless and connection-oriented transport protocols with examples?

• A. Connection-oriented (TCP) uses datagrams without a session; connectionless (UDP) establishes a persistent session.
• B. Connectionless (UDP) sends independent datagrams; connection-oriented (TCP) establishes a session with reliability.
• C. Connectionless protocols always guarantee delivery without ordering.
• D. Connection-oriented protocols never establish a session.

Answer: (B)

The key idea is how each transport model handles conversations and reliability. In a connectionless setup, each message is treated independently; there’s no persistent session or state kept to guarantee delivery or ordering. UDP is the classic example: you send individual datagrams without establishing a ongoing connection, so delivery and order aren’t guaranteed.

In a connection-oriented setup, a session is established before any data is exchanged. The protocol maintains state for that conversation and provides reliability features such as sequencing and retransmission, ensuring data arrives intact and in order. TCP is the example here: it performs a three-way handshake to establish a connection and then delivers a reliable, ordered byte stream with flow and congestion control.

That combination—independent datagrams for connectionless and a session-based, reliable transfer for connection-oriented—best captures the distinction. The other statements misstate how sessions and reliability work: connection-oriented protocols do establish a session; UDP does not guarantee delivery or ordering; and connection-oriented protocols do establish sessions.