There are three types of applications that are best suited for UDP:
- Applications that can tolerate some data loss, but require little or no delay
- Applications with simple request and reply transactions
- Unidirectional communications where reliability is not required or can be handled by the application
Many video and multimedia applications, such as VoIP and Internet Protocol Television (IPTV) use UDP. These applications can tolerate some data loss with little or no noticeable effect. The reliability mechanisms of TCP introduce some delay that can be noticeable in the quality of the sound or video being received.
Other types of applications well suited for UDP are those that use simple request and reply transactions. This is where a host sends a request and may or may not receive a reply. These types of applications include:
- DNS - May also use TCP
Some applications handle reliability themselves. These applications do not need the services of TCP, and can better utilize UDP as the transport layer protocol. TFTP is one example of this type of protocol. TFTP has its own mechanisms for flow control, error detection, acknowledgements, and error recovery. It does not need to rely on TCP for those services.