What does UDP mean?

UDP explained

UDP stands for User Datagram Protocol, and it is a popular communications protocol that offers a high-speed solution. It is used for producing low-latency and loss tolerating connections between the different applications on the Internet.

User Datagram Protocol boosts the speed of the communication process by allowing the transfer of data before the receiver provides an agreement. For that reason, User Datagram Protocol is the preferred option for time-sensitive communications, such as Domain Name System (DNS) lookup, Voice over IP (VoIP), video or audio transmissions.

How does it work?

UDP divides each message into multiple packets named datagrams and transfers them over the different network devices, like routers, switches, security gateways, until they reach their target host or server.

For distinguishing the queries of the users, each datagram holds a header with precise port numbers. In addition, it provides a checksum choice, which serves for verifying that the data transfer is complete. That is essential because User Datagram Protocol splits the messages, yet it doesn’t put them back together, and it doesn’t number them.

The most attractive feature of User Datagram Protocol is exactly that it offers high-speed communication. That is due to the fact it is a connectionless protocol. It boosts the speed of the transfer, but packets can get lost, and there is a potential for a DDoS attack to occur.

Applications relying on UDP

UDP and DNS 

DNS (Domain Name System) implements a group of different protocols, and one of the essential ones is exactly the User Datagram Protocol. Here are some of the key reasons why DNS uses User Datagram Protocol:

  • Thanks to User Datagram Protocol, DNS optimizes its work by implementing it for sending small data packets. That is very beneficial for the process of DNS resolution. The DNS queries for DNS data (DNS records) are mostly small, and UDP is able to transfer them quickly. 
  • DNS provides quick answers because UDP allows the transfer of data without completing a handshake process. The Domain Name System values that!
  • User Datagram Protocol is able to support a large number of DNS users simultaneously, thanks to the absence of connection conditions. On the other side, for instance, TCP has Receive and Send buffers.


UDP and TCP are probably the most popular protocols out there. Both of them run on top of IP – UDP/IP and TCP/IP. Yet, they are very different.

  • UDP is connectionless, and TCP is a connection-oriented protocol.
  • TCP is considered a reliable protocol because it ensures the delivery of data packets. UDP does not guarantee the delivery of the packets.
  • TCP implements a three-way-handshake procedure. UDP does not wait for agreement.
  • UDP is way quicker than TCP. That is because it does not involve error checking, flow control, or guarantee. 
  • TCP includes a flow control mechanism that does not allow a lot of packets to be sent to the destination simultaneously. User Datagram Protocol does not follow such a mechanism.

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