GSEC · Question #85
If a DNS client wants to look up the IP address for good.news.com and does not receive an authoritative reply from its local DNS server, which name server is most likely to provide an authoritative…
The correct answer is A. The news.com domain name server. DNS resolution follows a hierarchy from root to TLD to authoritative domain servers. The news.com nameserver holds the zone records for its subdomains.
Question
If a DNS client wants to look up the IP address for good.news.com and does not receive an authoritative reply from its local DNS server, which name server is most likely to provide an authoritative reply?
Options
- AThe news.com domain name server
- BThe .com (top-level) domain name server
- CThe .(root-level) domain name server
- DThe .gov (top-level) domain name server
How the community answered
(43 responses)- A74% (32)
- B7% (3)
- C14% (6)
- D5% (2)
Why each option
DNS resolution follows a hierarchy from root to TLD to authoritative domain servers. The news.com nameserver holds the zone records for its subdomains.
The news.com domain nameserver is authoritative for the news.com zone, which includes all subdomains such as good.news.com. Because it holds the actual zone file containing the A record for good.news.com, it is the only server that can return an authoritative answer for that fully qualified domain name.
The .com TLD nameserver only delegates queries to the authoritative nameserver for news.com and does not hold resource records for specific subdomains.
Root nameservers only know about TLD delegations and direct resolvers to the appropriate TLD server, not individual domain or subdomain records.
The .gov TLD nameserver has no authority over .com domains and is entirely unrelated to the resolution of good.news.com.
Concept tested: DNS resolution hierarchy and authoritative nameservers
Source: https://learn.microsoft.com/en-us/windows-server/networking/dns/dns-top
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