DNS uses TCP and UDP


In this post, I explain why some services use both the protocols TCP and UDP. DNS which is one such service stands for Domain Name System. It is a decentralized naming system for computers, services, or any resource connected to the internet or a private network. DNS translates a human-readable domain name such as into IP addresses such as This enables computers to identify one another on the internet, like Please see how to Hide Folders / Files from Search Results in Windows 10 and Windows 11, Domain Name System: How to create a DNS record, and How to Create a Linux Virtual Machine Via Azure CLI, Install an Nginx Web-Server and Configure TCP Port. In this article, you will learn how DNS uses TCP and UDP.

Does DNS use TCP and UDP?

On the question of whether DNS uses TCP and UDP. The answer is yes, DNS work on both TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). The DNS (Domain Name System) is one such example.

Other services that work on both TCP and UDP include DHCP (Dynamic Host Configuration Protocol), SNMP (Simple Network Management Protocol), and TFTP (Trivial File Transfer Protocol). Please see DNS: Unable to register a client to Domain, and Active Directory Ports: Service and network port requirements for Windows.

The domain name to IP address mappings is kept up to date in a distributed database by DNS. A user’s web browser sends a DNS query to a DNS server when they input a domain name to get the IP address connected to the domain name. The IP address is provided to the browser so that it can connect to the server hosting the website if the DNS server has the mapping stored in its database. Read how to set up a third-party DNS server on a Linux Server. You can also learn about how to activate DNS over TLS in Windows 11.

DNS is a critical component of the internet infrastructure. It is responsible for ensuring that users can access websites and other internet resources using human-readable domain names. The A-Z of Domain Name System: All you need to know about DNS is a great post you might also be interested in reading about. DNS Bad key 9017: The Cluster Name registration failed of one or more associated DNS names

How DNS Works on TCP and UDP?

When a client sends a DNS query to a DNS server, it can use either TCP or UDP as the transport protocol. The choice of transport protocol depends on the size of the DNS response that is expected. If the DNS response is expected to be larger than the maximum size of a UDP packet (which is 512 bytes), then the client will use TCP as the transport protocol. Otherwise, the client will use UDP. DNS inquiries can be ordinary (primary) or reverse, using TCP for zone transfer and UDP for names. While TCP is required to share data greater than 512 bytes, UDP can be used to exchange fewer data.

How to Specify DNS server ports in LAN TCP/IP settings on Windows?

To specify a DNS server port other than port 53 in the LAN TCP/IP settings on Windows, follow the below steps:

Step 1: Navigate to the Control Panel and click on Network and Sharing Center

Configuring DNS Port

Step 2: Click on Change adapter settings

Changing Adapter Settings

Step 3: Right-click on the adapter that you want to configure and select “Properties”

Wi-Fi Properties

Step 4: Double-click on Internet Protocol Version 4 (TCP/IPv4) or Internet Protocol Version 6 (TCP/IPv6) if you’re using IPv6 to open the properties dialog box.

IPv4 Properties

Then, provide the DNS server’s IP address and port number by choosing the Use the following DNS server addresses option. If the DNS server’s IP address is the Google Public DNS IP addresses and its port number is 54, for instance, you would type in the Preferred DNS server section.

IPV4 properties
IPV4 properties

When you’re done, click OK to save the changes.

Be aware that if your router also serves as a DNS server, you might need to make similar adjustments to its settings.

Furthermore, it’s crucial to remember that port 53 is the default port for DNS. Using a different port for DNS could cause problems with specific programs or services.

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