What is a PTR record?

A PTR (Pointer) record is a DNS record used for reverse DNS lookup — it maps an IP address back to a domain name. Unlike A records (domain → IP), PTR records go the other direction (IP → domain). They are stored in the special in-addr.arpa zone for IPv4 and ip6.arpa for IPv6.

Why are PTR records important for email?

Mail servers use PTR records to verify sender identity as part of spam filtering. If your mail server IP does not have a PTR record, or the PTR hostname does not match the forward A record, many receiving mail servers will reject or flag your emails as spam.

How do I set up a PTR record?

PTR records are managed by the owner of the IP address block, usually your hosting provider or ISP — not your domain registrar. To set up a PTR record, contact your server hosting provider or VPS provider and ask them to configure reverse DNS for your IP address to point to your desired hostname.

PTR Records

PTR (Pointer) records provide reverse DNS lookup, mapping IP addresses back to domain names. They're essential for email server verification and server identification.

How PTR Records Work

While regular DNS (A/AAAA records) maps domain names to IP addresses, PTR records do the opposite — they map IP addresses to domain names.

PTR Record Format

For IP address 192.0.2.1:

1.2.0.192.in-addr.arpa.  PTR  example.com.

IPv4 Reverse Lookup

Reverse the IP octets
Append .in-addr.arpa.

IPv6 Reverse Lookup

For IPv6, each nibble (4 bits) is reversed:

2001:db8::1
-> reverse: 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2
-> PTR: 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.

Common Uses

Email Server Verification - Many mail servers check PTR records to verify sender
Server Identification - Helps identify servers in logs
Security - Used in spam filtering and network forensics

Best Practices

Always set PTR records for mail servers
Ensure forward DNS (A record) matches reverse DNS
Use descriptive hostnames
TTL should be reasonable (3600-86400 seconds)

Testing PTR Records

Use our PTR Lookup tool or the Reverse IP Lookup to verify your PTR records.

Try it on your domain

See the theory in practice — run a PTR Lookup for your own domain.