Reverse DNS Lookup

Reverse DNS Lookup finds all domain names that have pointed to a given IP address - the inverse of a normal DNS query. Instead of "what IP does this domain resolve to?", it answers "what domains have resolved to this IP, pointed to this nameserver, or aliased to this CNAME target?". WhoisFreaks indexes 6.5B+ hostnames, so the result set covers historical A records and current configurations in one query.

A PTR record lookup returns the single hostname configured in the in-addr.arpa zone by the IP owner - typically the server's hostname set by the hosting provider. Reverse DNS Lookup (as offered by WhoisFreaks) searches the full DNS database to find all domains that have had A records pointing to that IP, giving a much broader result set.

Key use cases include: mapping shared hosting environments (to see which domains co-host on the same IP), threat intelligence pivoting (identifying all domains on a malicious IP), identifying CDN infrastructure, verifying email sender configuration, and network forensics.

Yes. Many shared hosting servers host hundreds or thousands of websites on the same IP. Reverse DNS reveals all co-hosted domains, which is valuable for security research (finding malicious neighbors) and competitive analysis.

Most public IP addresses are supported. Private/internal IP ranges (RFC 1918: 10.x.x.x, 172.16.x.x, 192.168.x.x) and some specialized addresses won't return meaningful results as they aren't publicly routed.

WhoisFreaks continuously collects DNS records. Results reflect all historical mappings stored in the database, including past A records - not just the current live configuration. This is especially useful when a domain has moved to a new IP but you want to find its old hosting neighbors.

This tool performs reverse CNAME lookup - finding all domains pointing to a given CNAME target. To look up the CNAME record of a specific domain (the forward direction), use the DNS Lookup tool.