Which two statements about UDP are correct? (Choose two.)

LPIC-1 Exam 102-500, objective 109. Networking fundamentals medium

Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.

Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.

How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.

The options

Choose 2.

Correct It is connectionless: a datagram is sent without first establishing a session

Correct. UDP has no handshake and no connection state. The sender simply emits a datagram to an address and port.

Not correct It guarantees that datagrams arrive in the order they were sent

Wrong. UDP offers no ordering. Datagrams may arrive out of order, duplicated, or not at all; any ordering must be built by the application. Sequencing is a TCP feature.

Correct It is the transport ordinary DNS queries use by default

Correct. A normal DNS query and its reply are a single small exchange, which suits UDP; the client falls back to TCP only for truncated responses and zone transfers.

Not correct It opens a connection with a three-way handshake before sending data

Wrong. The SYN, SYN-ACK, ACK handshake is TCP's. UDP has nothing equivalent.

Not correct It retransmits any datagram that is not acknowledged

Wrong. UDP neither acknowledges nor retransmits. That absence is exactly why it is faster and lighter, and why applications such as VoIP prefer it.

Why

UDP is a thin wrapper over IP that adds only ports and a checksum: connectionless, unordered, unacknowledged. TCP adds the handshake, sequence numbers, acknowledgements, retransmission and flow control, at the cost of latency and overhead. Services built on UDP include DNS queries, DHCP, NTP, TFTP and SNMP; SSH, HTTP, HTTPS, SMTP and FTP use TCP.

Where this comes from

Cited
LPI exam objective 109.1
What it says
Distinguish the properties of TCP from those of UDP.

Practise this

Reading one question is not practice. The trainer will draw a short set from objective 109 and space the ones you get wrong.

Practise LPIC-1 Exam 102-500

More questions on this objective

All questions on Networking fundamentals

Practise LPIC-1 Exam 102-500