PTR Record

    DNS record used for reverse DNS lookups, mapping an IP address back to a domain name.

    A PTR record (Pointer Record) is the DNS record type used for reverse DNS lookups. Instead of mapping a domain name to an IP address as a forward record does, it maps an IP address back to a domain name.

    PTR records are stored in special reverse DNS zones: in-addr.arpa for IPv4 and ip6.arpa for IPv6. The address is reversed and concatenated with the zone — for example, the IPv4 address 192.0.2.10 becomes 10.2.0.192.in-addr.arpa. This lets the standard DNS hierarchy answer queries about who owns a given address.

    PTR records are particularly important for mail servers, spam filtering and server identity. Many receiving mail servers reject or downgrade messages from senders whose forward DNS, reverse DNS and HELO/EHLO hostname do not agree, since mismatches are a common signature of spam infrastructure.

    For this reason PTR records are typically evaluated together with MX records, SPF, DKIM and DMARC when assessing the legitimacy of an inbound mail server.

    Points clés

    • Used for reverse DNS lookups
    • Maps IP addresses back to domain names
    • Stored under in-addr.arpa and ip6.arpa
    • Commonly used by mail servers
    • Helps validate server identity
    • Important for spam filtering and reputation
    • Often checked together with SPF, DKIM and DMARC
    • Supports both IPv4 and IPv6

    Termes associés

    Reverse DNSDNSMX RecordSPFDKIMDMARCIP AddressIPv4IPv6

    Outils associés

    DNS LookupMX Lookup