Reverse DNS Lookup

Reverse DNS (rDNS) is the process of resolving an IP address back to a hostname. While forward DNS translates domain names like google.com into IP addresses, reverse DNS does the opposite -- finding the hostname associated with an IP address by querying PTR records.

What are PTR Records?

PTR (Pointer) records are DNS records that map an IP address to a hostname. They are stored in a special reverse DNS zone (e.g., in-addr.arpa for IPv4 or ip6.arpa for IPv6). PTR records are typically configured by the IP address owner or their ISP.

Forward DNS vs Reverse DNS

Common Use Cases

• Email deliverability -- mail servers check PTR records to verify sender legitimacy
• Network troubleshooting -- identify which server or service owns an IP address
• Security analysis -- verify that an IP address legitimately belongs to the claimed organization
• Log analysis -- convert IP addresses in server logs to readable hostnames
• Anti-spam filtering -- IPs without PTR records are often flagged as suspicious

Forward Verification

This tool performs forward-confirmed reverse DNS (FCrDNS). After finding a hostname via PTR lookup, it resolves that hostname back to an IP to confirm the match. A verified result means the hostname's A/AAAA records point back to the original IP, confirming the association is legitimate.