Which DNS record type is used in reverse DNS lookup zones?
Short answer
A PTR
Question
Key Takeaways
This question tests your knowledge of DNS record types and their specific functions, with the common trap being to confuse PTR (reverse lookup) with A or AAAA records (forward lookup).
The correct answer is the PTR record, which maps IP addresses to domain names, and community consensus confirms that PTR is the main record type in reverse DNS lookup zones.
Common mistake: AAAA is the most common wrong answer because it is an IP address-related record, but AAAA maps hostnames to IPv6 addresses, while PTR is the only record used for reverse DNS lookups.
Expert Analysis
Why the Answer Is Correct
The PTR (pointer) record is used in reverse DNS to resolve an IP address to a domain name, which is the opposite of what an A record does. In a reverse DNS lookup zone, the IP address is reversed and appended with '.in-addr.arpa' (or '.ip6.arpa' for IPv6), and PTR records provide the corresponding hostname. Community comments, such as comment [2], accurately explain that a PTR record provides the domain name associated with an IP address and is used in reverse DNS lookups. Comment [1] also correctly notes that PTR records are used for reverse lookup checks.
Why the Other Options Are Wrong
AAAA is an IPv6 address record used in forward lookup zones to map hostnames to IPv6 addresses, not for reverse lookups. CNAME records create aliases for canonical names and are not used for IP-to-hostname resolution. TXT records store arbitrary text, such as SPF or DKIM data, and are not related to reverse DNS. Comment [3] confirms this reasoning: "We know it's not TXT or AAAA, narrows it down to two. CNAME gives us the DNS canonical name, has nothing to do with dns zone."
Community Comment Notes
The community overwhelmingly supports PTR, with 100% of votes for answer A. The most useful comments make the function clear: comment [1] describes PTR as providing "Domain with an IP address - aka reverse lookup checks," while comment [2] gives a fuller explanation of the PTR record's role. Comment [3] helps by eliminating distractors and pointing out that CNAME is unrelated, reinforcing the unique purpose of PTR in reverse DNS zones.
Official Reference
- https://datatracker.ietf.org/doc/html/rfc1035
- https://datatracker.ietf.org/doc/html/rfc1033
- https://www.ietf.org/rfc/rfc2317.txt
These links open the official vendor documentation in a new tab.
Exam Strategy
On DNS record type questions, first identify the direction of resolution: forward lookups map names to IPs (A, AAAA), while reverse lookups map IPs to names, which always uses PTR. Eliminate wrong answers by their purpose—CNAME for aliases, TXT for metadata, AAAA for IPv6 forward resolution—and you will safely land on PTR.
Community Votes
100% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 3 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 3
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priestb3 👍 4 Answered APTR record provides Domain with an IP address - aka reverse lookup checks
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ImpactTek 👍 3A DNS pointer record (PTR for short) provides the domain name associated with an IP address. A DNS PTR record is exactly the opposite of the 'A' record, which provides the IP address associated with a domain name. DNS PTR records are used in reverse DNS lookups.
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priestb3 👍 2 Answered AWe know it's not TXT or AAAA, narrows it down to two. CNAME gives us the DNS canonical name, has nothing to do with dns zone. PTR by default, google says the same thing
Reader comments & corrections
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