UDP

UDP (User Datagram Protocol) is one of the two main transport protocols utilized in IP networks.
The UDP protocol exists on the Transport Layer of the OSI Model.
The UDP protocol is an unreliable connectionless protocol.
When we say that UDP is unreliable, we mean that UDP does not provide mechanisms for error detection and error correction between the source and the destination. Because of this, UDP utilized bandwidth more efficiently than TCP. Applications which utilize UDP and which require reliable transport must provide their own error detection and correction mechanisms.
By connectionless, we mean that a network node can communicate with another network node using UDP without first negotiating any kind of handshaking or creating a connection. Because of this, UDP is very efficient for protocols that send small amounts of data at irregular intervals.
These properties of UDP are in contrast to TCP, which is connection-oriented and provides end-to-end reliability.
Higher layer protocols which utilize UDP include DNS, BOOTP, DHCP, SNMP, and RADIUS.
Diagram of the UDP Header
UDP Header Format
-----------------

0 7 8 15 16 23 24 31
+--------+--------+--------+--------+
| Source | Destination |
| Port | Port |
+--------+--------+--------+--------+
| | |
| Length | Checksum |
+--------+--------+--------+--------+
| +
| data octets ... +
+-----------------------------------+

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