PTR
Pointer (Reverse DNS)
PTR records map an IP address back to a hostname. Learn how reverse DNS works, why it matters for email deliverability, and how to request one.
Published · Last verified · Maintained by TamingDNS
PTR
Email Delivery
RFC 1035
Yes
PTR <hostname>.
PTR mail.example.com.
3600-86400 s; managed by your ISP or hosting provider, not in your own zone
💬 What This Record Does
A PTR (pointer) record is the reverse of an A record. It points an IP address back to a hostname. Reverse DNS (rDNS) is stored in the special ".in-addr.arpa" zone for IPv4 or ".ip6.arpa" for IPv6. PTR pointer records are managed by whoever owns the IP block (your ISP or hosting provider), not by you in your own domain zone. For email, many receiving servers require that your sending IP has a PTR record that matches its forward A record. This is called FCrDNS (Forward-Confirmed reverse DNS).
Common Uses
- Proving that a mail server IP belongs to a legitimate operator (FCrDNS check)
- Identifying which hostname is associated with an IP in server logs
- Improving email deliverability. Many spam filters penalise missing PTR records
⚠️ Watch Out For
- You cannot set PTR records in your own DNS zone. They must be configured by the IP block owner.
- A mismatch (PTR hostname doesn't resolve back to the original IP) breaks FCrDNS and can cause mail rejection.
- Shared hosting IPs often have generic PTR records. This can hurt deliverability. Use a dedicated IP where possible.
🔧 Related Tools
📋 Complete Example Records
Whole records in zone-file form: name, TTL, class, type, then the data. Most DNS panels ask for the pieces separately. Look them up live with the DNS Lookup tool.
10.2.0.192.in-addr.arpa. 3600 IN PTR mail.example.com.
Reverse DNS for 192.0.2.10. The octets run backwards under in-addr.arpa, and this record lives with whoever owns the IP block, not in your own zone.
10.2.0.192.in-addr.arpa. 3600 IN PTR mail.example.com. mail.example.com. 3600 IN A 192.0.2.10
These two lines are both halves of an FCrDNS check. The PTR names a host, and that host resolves back to the same address, which is what receiving servers verify.
0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa. 3600 IN PTR mail.example.com.
The IPv6 form for 2001:db8::10, one nibble per label in reverse under ip6.arpa. Set it before you start sending over IPv6.
10.2.0.192.in-addr.arpa. 3600 IN PTR server42.hosting.example.net.
This resolves correctly and still does you no good. The FCrDNS check passes, but a generic provider name tells a receiver nothing about who is sending.