PTR Record
DNSPTR Record is a DNS record type that maps an IP address back to a hostname, providing reverse DNS (rDNS) lookup. It is stored in special reverse-mapping zones (in-addr.arpa for IPv4 and ip6.arpa for IPv6) and is commonly used by mail servers and security systems to validate the identity of sending hosts and reduce spoofing and spam.
How It Works
A PTR record performs the opposite function of an A or AAAA record. Instead of translating a domain name into an IP address, it translates an IP address into a domain name. Reverse lookups are queried under dedicated DNS namespaces: IPv4 addresses are reversed and placed under in-addr.arpa (for example, 203.0.113.10 becomes 10.113.0.203.in-addr.arpa), while IPv6 uses ip6.arpa with nibble-reversed notation.
PTR records are typically controlled by whoever owns the IP address allocation, not necessarily the domain owner. In web hosting, that is often the hosting provider or the data center that assigns your server IP. Many control panels let you request or set rDNS for dedicated IPs, while shared IPs may have a fixed PTR. For email deliverability, the PTR hostname should usually have a matching forward record (A/AAAA) pointing back to the same IP, creating forward-confirmed reverse DNS (FCrDNS).
Why It Matters for Web Hosting
PTR records matter most when your hosting plan sends email (transactional mail, newsletters, app notifications) from your server IP. Many receiving mail systems check rDNS and may treat mail from IPs without a valid PTR, or with mismatched forward and reverse DNS, as suspicious. When comparing hosting options, consider whether you get a dedicated IP, whether rDNS can be set, and who is responsible for managing it.
Common Use Cases
- Improving email deliverability by providing valid reverse DNS for outbound mail servers
- Supporting anti-spam and anti-abuse checks that verify IP-to-hostname identity
- Troubleshooting network services by identifying hosts from IP addresses in logs
- Meeting requirements of some SMTP relays, security gateways, and compliance policies
- Documenting ownership and purpose of dedicated IP addresses in multi-server environments
PTR Record vs A Record
An A record maps a hostname to an IPv4 address (forward DNS), while a PTR record maps an IPv4 or IPv6 address back to a hostname (reverse DNS). A records are managed in your domain DNS zone, but PTR records are managed in the reverse zone owned by the IP holder. For best results with email and trust signals, the PTR hostname should resolve via A/AAAA back to the same IP.