PTR record
also: Pointer record, reverse DNS record, rDNS
A DNS Pointer record that maps an IP address back to a hostname, enabling reverse DNS lookups. It's the opposite of an A record.
A PTR (Pointer) record is a DNS record type that performs reverse DNS resolution—translating an IP address into a human-readable hostname. While standard A records map names to IPs (example.com → 192.0.2.1), PTR records do the opposite (192.0.2.1 → example.com).
PTR records are stored in special reverse DNS zones using the in-addr.arpa domain. For example, the IP 192.0.2.1 would have its PTR record in the 2.0.192.in-addr.arpa zone, with the octets reversed.
Common uses include email server validation (spam filters check if sender IPs have matching PTR records), server identification, and logging. You can query PTR records using nslookup or dig -x 192.0.2.1.