Pointer Record (PTR)
Maps an IP address to a hostname — used for reverse DNS lookup.
Standards: RFC 1035
What is a DNS PTR record?
PTR (Pointer) records enable reverse DNS: they map an IP address back to a hostname. For IPv4, the address is reversed and appended with .in-addr.arpa. For example, 192.0.2.1 becomes 1.2.0.192.in-addr.arpa → hostname. For IPv6, each nibble is reversed and appended with .ip6.arpa. PTR records are controlled by the IP address owner (usually your hosting provider), not by your domain registrar. To set a PTR record you must contact your server's hosting provider and request they configure it. PTR records are important for email deliverability: many mail servers reject or spam-score email from IPs without a valid rDNS record, or where the PTR does not match the A record ("forward-confirmed reverse DNS", FCrDNS).
Record Structure
| Field | Description |
|---|---|
| Name | Reversed IP address + .in-addr.arpa (IPv4) or .ip6.arpa (IPv6) |
| TTL | Time to live |
| Class | IN |
| Type | PTR |
| PTRDNAME | The hostname this IP maps to, e.g. mail.example.com. |
Examples
1.2.0.192.in-addr.arpa. 3600 IN PTR mail.example.com.
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa. 3600 IN PTR host.example.com.
Common Issues & Fixes
Email rejected — no PTR record for sending IP
Receiving mail servers check for valid rDNS on the sending IP. Missing PTR causes rejection or spam classification.
✓ Fix: Contact your hosting provider to add a PTR record for your mail server's IP pointing to your mail hostname.
PTR record and A record do not match (FCrDNS failure)
PTR points to hostname.example.com but A record for that hostname points to a different IP.
✓ Fix: Ensure the PTR → hostname and hostname A → IP form a consistent loop.