UDP Header Decoder

Paste a raw 8-byte UDP header in hex and decode ports, length, and checksum.

UDP header hex (≥ 8 bytes)

Source port53

Destination port50104

Length28

Checksum0x2A9C

How to read the result

UDP headers are exactly 8 bytes: source port, destination port, total length, and checksum. No flags or sequence numbers — that simplicity is why DNS and streaming use it.

Example

0035c3b8001c2a9c → src 53 (DNS), dst 50040, len 28

FAQ

How many bytes do I need?

Exactly 8 bytes (16 hex chars) for the header; extra bytes are payload.

Why is port 53 special?

Port 53 is DNS — most short UDP datagrams to/from 53 are DNS queries.