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Reverse DNS (PTR) Lookup

Find hostnames configured for an IP address using PTR records
Reverse DNS (PTR) Lookup

Enter an IP address to check whether it has a PTR record (reverse DNS). This can reveal a hostname that the IP owner configured.

What is reverse DNS used for?

Reverse DNS (PTR) is commonly used for email reputation, spam checks, troubleshooting, and basic validation. Many mail servers expect a PTR record that matches the sending IP.

When reverse DNS helps

  • Validating mail server identity
  • Investigating abuse reports
  • Mapping IPs to hostnames in logs

Learn more about PTR records or explore CGNAT IP address range and ASN in networking.

Related Articles

Reverse DNS Lookup: PTR Records Explained7 min read • January 9, 2026PTR Record Explained (Reverse DNS in Plain English)6 min read • January 9, 2026Understanding DNS: The Internet's Phone Book10 min read • November 9, 2025

Frequently asked questions

What is a Reverse DNS (PTR) lookup?
A reverse DNS lookup maps an IP address back to a hostname using a PTR record in DNS. It answers: "what hostname is configured for this IP?"
Why does reverse DNS matter?
Reverse DNS is commonly used for email reputation checks, troubleshooting, and basic validation. Many mail systems expect a PTR record for sending IPs.
Can reverse DNS identify the real owner of an IP?
Not reliably. A PTR record is configurable metadata and can be missing, generic, or misleading. For ownership, combine ASN/ISP data and WHOIS sources.
Why is my PTR record empty or "no PTR record"?
Many IPs do not have a PTR record configured. For residential and mobile networks it's common to have generic hostnames or none at all.
How do I change a PTR record?
PTR records are managed by the network that controls the IP range (often your ISP or hosting provider). You typically request changes through their support panel or ticketing system.