Why does DNS use UDP?

The Internet, and more specifically, DNS, is a constant communication process. Therefore there is a permanent exchange of data. There are different alternatives for transferring data through the Internet protocol (IP), UDP, TCP, RSVP, etc. Today, we will go around the user datagram protocol (UDP).

User Datagram Protocol (UDP) – fully explained

What is DNS?

You are more related to DNS than you think you are. Briefly, the Domain Name System (DNS) is a database that converts domain names into long numerical sequences called IP addresses. Computers communicate among them using these numbers. Humans, we need an easier language to manage our daily Internet searches: domain names. 

Basically, DNS links domain names with their correct IP addresses. You are totally familiar with the process. Just you don’t see it. You connect to the Internet, then you type your favorite news’ site name. Your browser sends the request. The database (DNS) translates the name into an IP address for the machines to get it and work on the request. DNS will match the name and IP address correctly. Your news site will get loaded.

What is UDP?

The user datagram protocol (UDP) is a communication protocol designed for exchanging messages between devices and networks. High-speed communication is its main and attractive feature.

It’s a very convenient protocol for processes where time, fast speed, matters a lot—for example, DNS searches or video transmissions.

UDP was created in 1980, and since then, it’s a protagonist on the Internet’s tools suite for working efficiently.

How does UDP work?

User datagram protocol divides messages into datagrams or packets for transferring them through the different devices a network includes until their destination. Transferring small datagrams instead of big packets is faster. Besides, UDP doesn’t need to have a formal connection before the transfer. This factor also speeds the process a lot.

UDP has its downsides. Packets can get lost during the travel to reach their destination. This protocol breaks the messages into pieces (datagrams), but it doesn’t rebuild them again. It has a way not to confuse datagrams coming from different users’ requests (different numbers are set on every datagram header) and a checksum to verify if the transferred messages are complete, but that’s it. UDP also doesn’t confirm if the sent messages are received or not.

Handshaking is a common security process to verify certain requirements between devices before getting connected. UDP doesn’t include a handshake as a part of its operation. 

UDP’s simplicity makes it faster than other communication protocols but also less secure. It can open the door for dangerous DDoS attacks to occur. 

Why does DNS use UDP?

DNS works by using a complete set of tools and protocols. UDP is one of them, and it’s key for DNS because:

  • UDP allows DNS to optimize its work while using it exclusively to send smaller data packets. The limit to be transferred via UDP is 512 bytes. If there are bigger packets to be sent, a different protocol will be used. It’s very convenient for the DNS resolution process since DNS requests are mostly small data packets. They are ideal segments UDP can transfer fast.
  • DNS so values UDP’s fast speed. Being connection-less and skipping the handshake process allows DNS to respond really faster than it could do with other protocols.
  • UDP doesn’t need consistent data to work. This means valid data based on specific or defined rules. This means risks but also agility and, again, speed. No doubt DNS must offer consistency, and it does, through the use of other protocols. 
  • UDP’s lack of security can be complemented and fixed via alternative protocols and methods. DNS can take the best of UDP, minimizing the risks.


UDP is very useful for DNS. It’s a good example of teamwork importance. The key to getting the best out of UDP’s features is to complement its lacks with other tools (teammates). 

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