Reverse DNS (PTR) Lookup
Look up the DNS PTR record of an IPv4 address (or of a domain's A record) to find the hostname behind it. Missing or mismatched reverse DNS is a top cause of mail deliverability issues.
Frequently asked questions
What is a DNS PTR record?
The reverse of an A record: it maps an IP address back to a hostname. It lives under in-addr.arpa (the IP's digits reversed), so 203.0.113.7 is looked up as 7.113.0.203.in-addr.arpa. A reverse DNS lookup is a query for that PTR record.
Why does my mail server need a PTR record?
Gmail, Outlook and most corporate filters reject or spam-folder mail from IPs without reverse DNS, and many also check that the PTR hostname resolves back to the same IP (forward-confirmed reverse DNS). Set the PTR to the hostname your server greets with in SMTP.
How do I set up a PTR record?
Not at your DNS host: the reverse zone belongs to whoever owns the IP. On a VPS or cloud server, set it in the provider's panel (often called reverse DNS or rDNS); on a dedicated line, ask your ISP. Then run this lookup to confirm it.
Can I look up a PTR record for a domain?
Enter the domain and the checker resolves its A record first, then looks up the PTR of that IP. This tool checks IPv4 addresses.