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What is Authoritative DNS server?

The authoritative DNS server is the final holder of the IP of the domain you are looking for. When you write a domain name in your browser, a DNS query is sent to your internet service provider (ISP). The ISP has a recursive server, which might have the needed information cached in its memory. But if the data is outdated, this recursive server need to find the IP elsewhere. It will try to find it in other recursive servers, but if it can’t, it needs to get the IP address from an authoritative DNS server.

Authoritative DNS server

Such a server is the name server, which has the original zone records. It has been configured from the original source, and it returns answers to queries that have been predetermined by the administrator.
These DNS servers are giving responses to queries just for the zones they are configured. This makes them very efficient and fast. They will not respond to recursive queries too. The requests that reach them are from Resolving name servers (resolvers) and the authoritative servers will either have the complete answer or they will pass to the name server who is responsible for it.
The authoritative servers don’t cache query results. They have data that is saved in their system.
It can be master or slave. It can store the original zones records, or a secondary server which communicates directly with the primary and copies the records directly through a DNS mechanism.

The authoritative DNS servers can be where the website is hosted or where the DNS provider is.

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Authoritative DNS server vs. Recursive DNS server 

Both Authoritative DNS servers and Recursive DNS servers have crucial functions, and they depend on each other to fulfill their purposes. However, there are some fundamental differences between them. 

Authoritative DNS servers store the most recent and accurate information (DNS records) for a domain and are able to provide the final answers for users’ DNS queries (DNS lookups). On the other hand, Recursive DNS servers only keep a copy of the DNS information for a particular amount of time (TTL). Additionally, they often have to obtain the answer for a DNS query from another server. 

So let’s explain a little bit more about the differences between them!

An authoritative DNS server is responsible for answering DNS queries for a particular set of DNS zones by providing information from its own data. It does not have the need to reference another source. Most commonly, it replies to the requests with one of the following types of answers:

  • Authoritative DNS information (DNS records) from its own store. It could come from a master zone file, from a secondary zone duplicate transferred from a master server, from Dynamic DNS, etc.
  • In case it doesn’t know the answer, it is going to direct to another nameserver. For instance, the Root name server points to the responsible TLD (Top-Level Domain) server. 
  • An authoritative NXDOMAIN. It replies that the requested domain name doesn’t exist.
  • An authoritative empty NOERROR (NODATA) answer. The requested domain name exists, but the particular queried DNS record does not.

The Recursive DNS server replies to DNS queries by asking other nameservers for the needed information (DNS records). In some cases, this server responds to DNS requests directly from its cache if the information is available there. In case it is not, the Recursive DNS server, also known as DNS resolver, is going to perform a search and ask the responsible authoritative servers until it finds the needed answer.

Normally, Recursive DNS servers store in their cache memory information about previously queried domain names for further use. That really reduces the network traffic and improves the performance. 

Recursive DNS servers normally answer DNS queries in the following way:

  • Authoritative DNS information (DNS records) from its own store, if there is any. That could be a positive response, NXDOMAIN, or NOERROR/NODATA.
  • Non-authoritative DNS information that is received and cached from a previous recursive DNS query, if there is any.
  • Data retrieved from remote authoritative name servers. It can be further cached and reused for answering future DNS queries.

Recursive DNS servers are most commonly used to reply to general DNS queries for users on a local network.

How to get Authoritative DNS server for a domain?

It is actually very easy to get the Authoritative DNS server for a domain name. Here we are going to show you how by using popular tools such as Dig, NSlookup, Host, and WHOIS. 

  • Dig command

We are going to use the Dig command and request the NS records, where NS stands for nameserver. Therefore, this DNS record is going to show us which are the authoritative DNS servers for the particular domain name or DNS zone.

Type the following:

$ dig +short NS exampledomain.com

  • NSlookup command

NSlookup is another popular tool that can help you get the Authoritative DNS server for a domain name or a DNS zone. It works on Windows, Linux, and macOS. Once again, we are going to query the NS records.

Simply type the following:

$ nslookup -type=NS exampledomain.com

  • Host command

Host command is a beneficial tool that you can use on your Linux or macOS device. For our purpose, to get a list of the Authoritative DNS servers, we should request the NS record. 

Just write the following:

$ host -t NS exampledomain.com

  • WHOIS 

With the WHOIS command, you can get a list of the Authoritative DNS servers too. 

Write the following:

$ whois exampledomain.com | grep -i “Name .*:”

*Make sure to replace “exampledomain.com” with the one you want to check.

Conclusion

So now you are familiar with what the Authoritative DNS server actually is and its crucial purpose! Its ability to provide authoritative answers to the DNS requests (DNS queries) is one of the key fundamentals of the entire DNS (Domain Name System) and the Internet as well! 

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Article Name
What is Authoritative DNS server?
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What is Authoritative Name Server? - The Authoritative DNS server is the final holder of the IP of the domain you are looking for. It is the name server which has the original zone records.
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ClouDNS
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Tags: , , , , , Last modified: June 2, 2022
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