Reverse IP Lookup

Information about the Free Online Reverse IP Lookup Tool

Using our Big Free Tools Reverse IP Lookup, system administrators, cyber security researchers and SEO experts can reverse lookup any IPv4 or IPv6 address to find out the hostname (PTR record) and discover other domain names in the same physical server or virtual host.

Most commonly a DNS look up will turn a domain name into an IP address but a Reverse IP Lookup is the reverse and searches reverse DNS zones (in-addr.arpa for IPv4 and ip6.arpa for IPv6) as well as virtual host mappings, revealing what sits behind an IP address.

Key Use Cases for Reverse IP & PTR Checks

When your website is hosted on a shared server, thousands, hundreds of thousands of other domains may be sharing your IP. You may want to find out which domains are co-habiting with your website to make sure that none are associated with spam, phishing, or blacklisting.

Check Mail Server PTR Records (rDNS): Services like Gmail, Outlook and Yahoo will do a Reverse DNS check of the incoming mail server. If your server does not have a valid ptr record which points to an RFC compliant hostname, then your mail will probably get rejected or marked as spam.

Cybersecurity & Reconnaissance: Security researchers and penetration testers employ reverse IP lookups to examine the attack surface of a company, uncover abandoned subdomains or staging environments and discover common hosting on the same server (VPS).

Quickly determine if an IP points to an origin web server (cPanel, Lite Speed, AWS EC2, etc.) or to a reverse proxy / CDN edge node like Cloudflare, Fastly, Akamai, and more.

How to Conduct a Reverse IP Lookup

Enter an IP or Domain: Enter any public IP address (e.g. 8.8.8.8)-or enter a domain name and our tool will first resolve its IP for you automatically.

Press Lookup to search authoritative reverse DNS resolvers and host data on the fly.

See the main PTR hostname, underlying ISP/ASN network information, and any domains pointing to that IP.