Reverse DNS Lookup
Find the hostname associated with an IP address. PTR record lookup for reverse DNS verification.
rdns.sh
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What is Reverse DNS?
Reverse DNS (rDNS) is the process of resolving an IP address to a hostname — the opposite of a standard DNS lookup. It uses PTR (Pointer) records stored in the special in-addr.arpa domain for IPv4 and ip6.arpa for IPv6.
For example, the PTR lookup for 8.8.8.8 returns dns.google. Reverse DNS is critical for email deliverability — many mail servers reject emails from IP addresses that lack a valid PTR record pointing back to a legitimate hostname.
Frequently Asked Questions
A PTR (pointer) record maps an IP address to a hostname. It is the reverse of an A record. PTR records are stored under the in-addr.arpa domain (IPv4) or ip6.arpa domain (IPv6). They are managed by the IP address owner, not the domain owner.
Many mail servers check that the sending IP address has a valid PTR record (reverse DNS). If your IP lacks a PTR record or the hostname does not forward-confirm to the same IP, your emails may be marked as spam or rejected. ISPs and hosting providers can configure PTR records for your IP.
Contact your IP address owner (usually your hosting provider or ISP) and ask them to set a PTR record for your IP. Most hosting providers allow this through their control panel. Set the PTR value to your server's fully qualified domain name (FQDN).