Hello Adhithya
Yes, your understanding is correct. 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. In your example, 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, andthe authoritative server responds with the flag set, when the recursive resolver relaysthat inforamation, it will typically set the flag to 0.
Your understanding of the DNS resolution process is essentially correct, but there are a few nuances worth noting. The process begins when a client initiates a DNS request. The recursive resolver (local DNS server) first checks its cache to see if it already has the requested domain name. If it does, it responds to the client with the cached IP address and the authoritative flag set to zero. If the information is not in the cache, the recursive resolver queries the root server, which directs the query to the appropriate Top-Level Domain (TLD) server. The TLD server in turn directs the query to the authoritative name server for the domain in question. The authoritative server responds with the IP address of the domain name, which the recursive resolver caches before responding to the client. Finally, the client accesses the domain using the IP address it received from its local DNS resolver. So yes, your understanding is correct.
I hope this has been helpful!
Laz