DNS - Authoritative Flag

The Authoritative flag in a DNS response is set to zero (disabled) when the response is from a non-authoritative source such as a cache or a recursive resolver. If a DNS query is made to a domain like abc.com and the response is from a recursive resolver, the authoritative flag would indeed be set to zero. This is because the recursive resolver is not the authoritative source for the domain in question, it merely forwards the request to the appropriate authoritative server and returns the response it receives. Even if the recursive resolver made the request to an authoritative server, and the authoritative server responds with the flag set, when the recursive resolver relays that information, it will typically set the flag to 0.

Links

https://forum.networklessons.com/t/introduction-to-dns/1266/34?u=lagapidis

https://networklessons.com/cisco/ccna-200-301//introduction-to-dns