Reverse IP Lookup

What is Reverse IP Lookup?

Reverse IP Lookup is the process of taking an IP address and finding out which domains are hosted on that IP. It’s the reverse of DNS lookup, where you start with a domain and retrieve its IP address.

How Does Reverse IP Lookup Work?

Here’s a breakdown of how it works under the hood:

1. Querying PTR Records: Sometimes, the reverse DNS record (PTR) will directly map an IP to a domain.

2. Scanning Hosting Data: Public databases and passive DNS records are used to check which domains have pointed to the IP.

3. Web Crawling: Tools crawl IP-hosted servers and check for HTTP headers, certificates, or server response metadata.

4. Aggregated Hosting Data: Some services use real-time hosting snapshots or WHOIS data to map domains to IPs.

Reverse IP does not always guarantee 100% accuracy—domains may have recently migrated or use CDNs.

Practical Examples

Example 1: Finding All Sites on a Shared Host

Input:

IP: 192.185.30.10

Output:

- example-blog.com  
- myshopstore.net  
- vintagecars.org

Useful for: Competitor analysis or discovering clients hosted on a shared server.

Example 2: Security Audit

You’re investigating a suspicious IP used in phishing emails. Using reverse lookup, you find other domains on that IP, some of which are also flagged.

Use Case: Helps in threat intelligence and IP reputation checks.

Use Cases

• SEO: Identify if your site shares an IP with spammy or blacklisted domains

• Cybersecurity: Detect phishing, malware distribution, or malicious hosting clusters

• Hosting Insights: Evaluate server sharing in budget hosting or cloud setups

• Network Troubleshooting: Trace routing conflicts or misconfigured reverse DNS entries

Pro Tips

• Combine with DNS tools like DNS Lookup to map the full domain infrastructure.

• Use IP Address Validator to confirm your input IP is properly formatted before lookup.

• Check ownership: Use WHOIS tools in tandem to verify domain ownership or registrant details.

• Reverse IP lookups may not work on CDN-backed sites like Cloudflare; use direct origin IP when possible.

• Shared hosting can reveal dozens of unrelated domains—filter results by country or name server for relevance.