Reverse DNS Lookup

Resolve an IPv4 or IPv6 address to its PTR hostname (reverse DNS).

Resolves the PTR record in in-addr.arpa / ip6.arpa. No external API, nothing stored.

Related tools

DNS LookupDig-style lookup for A, AAAA, MX, TXT, NS, SOA, SRV, CAA, PTR — plus subdomain sweep.IP InfoReverse DNS plus ASN, network and country for an IP (via Team Cymru).WHOIS LookupRegistration, registrar, dates and nameservers for a domain (live WHOIS).IP Address ConverterConvert an IPv4 address between dotted, decimal, hex and binary, or expand IPv6.

Frequently asked questions

What is a reverse DNS (PTR) lookup?

A normal DNS lookup turns a name into an IP address. A reverse lookup does the opposite: it takes an IP and finds the PTR record that names the host, using the special in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones.

Why does an IP have no PTR record?

PTR records are optional and are controlled by whoever owns the IP block, not by the domain owner. Many residential and cloud IPs have no PTR, or one set by the hosting provider rather than the site.

Why is reverse DNS important for email?

Mail servers frequently reject or downgrade mail from IPs whose PTR record is missing or does not match the sending host name (forward-confirmed reverse DNS). A valid PTR is a basic deliverability requirement.

Does the PTR have to match the forward record?

For mail it should. Best practice is forward-confirmed reverse DNS (FCrDNS): the IP's PTR resolves to a host name, and that host name resolves back to the same IP.

Can one IP return several hostnames?

Yes. An address can have multiple PTR records, though for mail a single, consistent name is strongly recommended. This tool lists every PTR it finds.