UDP Header Illustration

The User Datagram Protocol (UDP) is a communications protocol that is primarily used to establish low-latency and loss-tolerating connections between applications on the Internet. UDP is used for time-sensitive transmissions such as video playback or DNS lookups. Unlike TCP, UDP is connectionless and does not guarantee reliable delivery, ordering, or error checking.

UDP Header

Source Port (16 bits) Destination Port (16 bits)
Length (16 bits) Checksum (16 bits)

Source Port (16 bits)

Identifies the sending port. Back to header

Destination Port (16 bits)

Identifies the receiving port. Back to header

Length (16 bits)

Specifies the length of the UDP header and data. Back to header

Checksum (16 bits)

Used for error-checking the header and data. Back to header