UDP

User Datagram Protocol operates at Layer 4 of the OSI model and sends datagrams with no connection setup, handshake, or ordered-delivery tracking. This makes it faster than TCP — no three-way handshake, no acknowledgments, no retransmission of lost segments. For the N10-009 exam, UDP suits traffic where a dropped packet beats a delayed one: DNS queries (port 53), DHCP (ports 67/68), TFTP (port 69), SNMP (port 161), and real-time media like VoIP and streaming. A common trap is assuming DNS always uses TCP; UDP is the default, while TCP handles responses over 512 bytes and zone transfers.