What is Authoritative and Non-authoritative DNS Server

What is Authoritative and Non-authoritative DNS Server? Understand the difference between Authoritative and Non-answer for DNS query in simple words.

What is Non-Authoritative DNS Server?

Non-authoritative name servers do not contain original source files of domain’s zone. They have a cache file for the domains that is constructed from all the DNS lookups done previously. If a DNS server responded for a DNS query which doesn’t have original file is known as a Non-authoritative answer.

For example, we query for DNS records of domain tecadmin.net and Google’s open DNS server 8.8.8.8 responded for this query which doesn’t contain domain’s original zone files. This answer is known as a Non-authoritative answer.

$ nslookup tecadmin.net

Server:         8.8.8.8
Address:        8.8.8.8#53

Non-authoritative answer:
Name:   tecadmin.net
Address: 104.27.189.217
Name:   tecadmin.net
Address: 104.27.188.217

What is Authoritative DNS Server?

An authoritative name server is a name server that has the original source files of a domain zone files. The is where domain administrator has configured the DNS records for a domain. Authoritative DNS server can be master DNS server or its slaves.

For example – domain tecadmin.net’s authoritative are alec.ns.cloudflare.com and athena.ns.cloudflare.com. If you directly query to these DNS servers, they will return authoritative answer because they have the original files of domain zone.

$ nslookup tecadmin.net alec.ns.cloudflare.com

Server:         alec.ns.cloudflare.com
Address:        173.245.59.59#53

Name:   tecadmin.net
Address: 104.27.188.217
Name:   tecadmin.net
Address: 104.27.189.217