Web Protocols

UDP (User Datagram Protocol)

A minimal, connectionless transport: no handshake, no ordering, no retransmission — just fast datagrams. The blank canvas QUIC builds reliability on top of to power HTTP/3.

What it is

UDP sends datagrams with almost no overhead: there is no connection setup and no built-in reliability or ordering. That makes it ideal for latency-sensitive traffic (DNS, real-time media) and as a foundation that a higher layer can build on. QUIC runs on UDP and adds its own reliable, ordered, encrypted streams.

Why it matters

  • Its lack of handshake and ordering makes it the fast base layer for QUIC and HTTP/3.
  • DNS and real-time protocols rely on its low latency.

Common mistakes

  • Firewalls blocking UDP/443, which silently disables HTTP/3.
  • Assuming UDP itself is unreliable in practice — protocols like QUIC add reliability on top.

How WebInspect checks this

  • WebInspect infers UDP-based transport (QUIC/HTTP/3) from protocol advertisement.