Does DNS Use TCP or UDP

Does DNS Use TCP or UDP?

4 mins

DNS stands for Domain Name System, which is a system used to translate domain names (like into IP addresses (like

When you type in a domain name into your web browser, your computer contacts a DNS server to look up the corresponding IP address.

The DNS protocol can use either TCP or UDP transport protocols. The primary use of TCP is for zone transfers, which are when a secondary DNS server updates its copy of the zone from the primary server.

The primary use of UDP is for name lookups, which are when a client wants to resolve a domain name into an IP address.

What is DNS Port and How Does it work?

DNS, or Domain Name System, is the system that allows humans to access websites using easy-to-remember domain names instead of difficult-to-remember IP addresses.

DNS works by translating domain names into IP addresses and vice versa. This process is known as DNS resolution. When you type a domain name into your web browser, your computer will contact a DNS server and request the IP address associated with that domain name.

The DNS server will then respond with the requested IP address, and your computer will connect to the website hosted at that address. DNS servers are used by ISPs to provide their customers with internet access, and they are also used by companies and organizations to provide internal network access.

There are many different types of DNS servers.

The most common type is the recursive DNS server.

  • Recursive DNS servers are able to resolve almost any kind of DNS query, which makes them particularly well suited for use by ISPs.
  • Another common type of DNS server is the authoritative DNS server. Authoritative DNS servers are only able to resolve queries for domain names that they are responsible for.

They are often used by companies and organizations to provide internal network access because they can be configured to allow or deny access to specific domains.

TCP or UDP – Which one Does DNS Use?

DNS uses UDP for the majority of its queries. The main reason for this is that UDP is a simpler protocol and provides less overhead than TCP. This makes it ideal for small, quick DNS queries.


However, UDP does have some limitations. It is not as reliable as TCP, and it does not provide any error-checking mechanism. This means that UDP packets can be lost or corrupted in transit.

As a result, DNS will sometimes use TCP for important queries, such as zone transfers between DNS servers. When using TCP, DNS will establish a connection with the server and then send a stream of data.

The server will acknowledge each packet to ensure that it has been received correctly. If any packets are lost or corrupted, the server will retransmit them. 

While this process is more reliable than UDP, it is also slower and more resource-intensive. As a result, TCP is usually only used for critical DNS queries.

Why Does DNS Use TCP?

DNS uses TCP for a few reasons.

  • First, unlike UDP, TCP is a reliable protocol, meaning that it ensures that data is delivered correctly and in the correct order. This is important for DNS because DNS packets contain critical information about website addresses and IP addresses.
  • Second, TCP is a connection-oriented protocol, which means that it maintains a connection between two devices while data is being transmitted. This is beneficial for DNS because it helps to ensure that data is not lost or corrupted during transmission.
  • Finally, TCP is a very efficient protocol, and it can handle large amounts of data without harming network performance.

For these reasons, DNS uses TCP to provide reliable and efficient service.

Why does DNS Use UDP?

DNS uses UDP for a variety of reasons.

  • For one, UDP is a connectionless protocol, which means that there is no need to establish a connection before sending data. This makes it ideal for applications like DNS that need to send small amounts of data quickly.
  • Additionally, UDP is a much simpler protocol than TCP, which makes it easier to implement and more efficient.
  • Finally, UDP is able to provide basic error-checking and recovery, which is important for ensuring that DNS queries are successfully received and processed.

Overall, the use of UDP allows DNS to provide a quick and reliable service with minimal overhead.

What is the Different Between TCP and UDP?

When it comes to computer networking, there are two main protocols that are responsible for how data is transferred between devices – TCP and UDP. Both have their own advantages and disadvantages.


So, it’s important to understand the difference between them in order to make the best decision for your needs. 

TCP, or Transmission Control Protocol, is a reliable connection-oriented protocol. This means that when data is sent using TCP, it is first divided into small packets.

These packets are then transmitted over the network, and they are reassembled into the original message once they reach their destination. Because of this extra layer of reliability, TCP is often used for mission-critical applications where data integrity is important. 

UDP, or User Datagram Protocol, is a less reliable but faster connectionless protocol. This means that UDP does not guarantee that all packets will arrive at their destination.

However, it can be faster since it doesn’t waste time transmissions. For this reason, UDP is often used for streaming applications like audio or video where some lost data isn’t as critical. 

So, which should you use – TCP or UDP? The answer depends on your specific needs. If you need guaranteed delivery of data with no loss, then TCP is the way to go. However, if you’re more concerned about speed than reliability, then UDP may be a better choice.

Final Thoughts

DNS is an incredibly important part of the internet, and its function is often taken for granted. It’s responsible for translating human-readable domain names into machine-readable IP addresses.

You may not think about it very often, but DNS is always working in the background to make sure you can find the websites you’re looking for. We’ve explained some of the basics of how DNS works and why it uses UDP instead of TCP.


Michael Fied

founder of and SpamBurner

Michael Fied is the founder and CEO of and SpamBurner. In addition, he’s an internationally top-rated and award-winning website advisor and website architect with a global team of 55. You can find Michael on LinkedIn or contact him directly here.

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