How is reliable data transfer ensured when using the UDP protocol?

UDP is a connectionless protocol without delivery guarantees, so additional methods are used for reliable data transmission over UDP:

• Retransmission: the sender resends packets if it does not receive acknowledgment from the receiver.
• Packet numbering: to detect losses and restore order.
• Integrity check: using checksums or hashes to verify data.
• Buffering and timeouts: to manage retries and wait for acknowledgments.
• Use of protocols over UDP: such as QUIC or RTP, which implement reliability at the application level.

Thus, reliability is achieved through additional logic at the application level or transport protocol over UDP.