What is a Reverse Zone in DNS?

• A. A zone that contains records mapping IP addresses back to domain names.
• B. A zone containing A records for forward mapping.
• C. A zone used for updates to MX records.
• D. A zone that stores DNSSEC signatures.

Answer: (A)

Reverse DNS zones are used to perform reverse lookups, turning an IP address back into a domain name. They contain PTR records that map an IP to a hostname. For IPv4, the data lives under in-addr.arpa with the octets reversed; for IPv6, under ip6.arpa. This mechanism is widely used by mail servers and logging systems to verify the identity behind an IP address.

Forward DNS zones, on the other hand, store A (and AAAA) records that map domain names to IP addresses. The other options describe different DNS data or purposes (such as MX record updates or DNSSEC signatures) that aren’t about reverse lookups.