PTR Lookup
PTR Lookup
Reverse DNS lookup for an IP address, with forward confirmation check. Missing or mismatched PTR records cause mail rejections.
Enter an IP address above to look up its reverse DNS
About this tool
- What is a PTR record?
- A reverse DNS record that maps an IP address to a hostname. While A records map hostname → IP, PTR records map IP → hostname. They live in the .arpa DNS zone and are managed by the IP address owner (your hosting or cloud provider).
- Why do I need a PTR record for email?
- Most receiving mail servers perform a reverse DNS lookup on the connecting IP. If no PTR record exists, or the PTR hostname doesn't forward-resolve back to the same IP, the server may reject the connection or classify it as spam.
- What is forward-confirmed reverse DNS?
- Also called FCrDNS. The IP resolves to a hostname (via PTR), and that hostname in turn resolves back to the same IP (via A/AAAA). Both directions must match. Most email servers require this for delivery.
- How do I add or change my PTR record?
- Contact your hosting or cloud provider — they control the IP space and are the only ones who can set PTR records for it. AWS, GCP, Azure, and DigitalOcean all have self-service rDNS settings in their console.