PTR records are created in which DNS zone?

PTR records are created in which DNS zone?

• A. Forward lookup zone
• B. Reverse lookup zone
• C. Cache zone
• D. Root zone

Answer: (B)

PTR records are used for reverse DNS lookups, which translate an IP address back into a host name. They belong in reverse lookup zones, not in forward lookup zones. In IPv4, the reverse zone is built under in-addr.arpa (and for IPv6 under ip6.arpa). The records map the reversed IP address to the canonical hostname, so a PTR entry answers the question “which name does this IP belong to?” For example, a 192.0.2.8 address would have a PTR record in the corresponding in-addr.arpa zone that points to the host name. Forward lookup zones, on the other hand, map names to IPs using A/AAAA records. Cache zones simply store recently resolved results and aren’t authoritative, and the root zone is the top of the DNS hierarchy rather than a place to store per-host PTR mappings.

PTR records are used for reverse DNS lookups, which translate an IP address back into a host name. They belong in reverse lookup zones, not in forward lookup zones. In IPv4, the reverse zone is built under in-addr.arpa (and for IPv6 under ip6.arpa). The records map the reversed IP address to the canonical hostname, so a PTR entry answers the question “which name does this IP belong to?” For example, a 192.0.2.8 address would have a PTR record in the corresponding in-addr.arpa zone that points to the host name. Forward lookup zones, on the other hand, map names to IPs using A/AAAA records. Cache zones simply store recently resolved results and aren’t authoritative, and the root zone is the top of the DNS hierarchy rather than a place to store per-host PTR mappings.