🌐 Reverse IP Lookup

What is Reverse IP Lookup? Reverse IP lookup finds all domain names that resolve to a specific IP address. This is useful for discovering websites hosted on the same server or IP. Common Use Cases: • Security research and reconnaissance • Identifying shared hosting environments • Finding related websites or domains • Investigating suspicious IP addresses • Discovering hidden or forgotten subdomains • Competitive intelligence gathering Types of Hosting: • Shared Hosting - Multiple domains on one IP • Dedicated Hosting - One domain per IP • VPS Hosting - Few domains per IP • Cloud Hosting - Dynamic IP allocation • CDN - Content delivery networks Limitations: • Some domains may use privacy protection • CDNs and load balancers can obscure real IPs • Dynamic DNS and cloud services change frequently • Not all domains may be discoverable • Results depend on data source completeness Security Considerations: • Reverse IP lookup is passive reconnaissance • Information is publicly available • Use responsibly and ethically • Respect rate limits and terms of service • Consider privacy implications Tools and Techniques: • DNS PTR record queries • Certificate transparency logs • Passive DNS databases • Search engine dorking • SSL certificate analysis

Command Line Tools: • nslookup -type=PTR IP - Reverse DNS lookup • dig -x IP - Reverse DNS with dig • host IP - Simple reverse lookup • whois IP - IP ownership information • nmap --script hostmap-* IP - Nmap host mapping Online Tools: • Certificate transparency logs (crt.sh) • Passive DNS databases (VirusTotal, PassiveTotal) • Search engines (Google, Bing dorking) • Specialized reverse IP services • SSL certificate analyzers API Services: • Shodan API for device discovery • Censys API for internet scanning • SecurityTrails API for DNS data • VirusTotal API for threat intelligence • PassiveTotal API for passive DNS