Reverse DNS Lookup - Find All Domains on an IP

A reverse DNS lookup discovers every hostname pointing to a specific IP address, revealing shared hosting relationships and infrastructure connections. Use robtex.com to find all domains on any IP.

Why Reverse DNS Matters

Forward DNS maps domain names to IP addresses. Reverse DNS does the opposite - and reveals far more than you might expect.

When multiple domains point to the same IP, they share infrastructure. This might be intentional (a company's multiple brands) or indicate shared hosting where hundreds of unrelated sites coexist on one server.

What Reverse DNS Reveals

  • All hostnames resolving to an IP - Every domain with A or AAAA records (IPv4 and IPv6)
  • Shared hosting density - How many sites share the server
  • Related domains - Patterns suggesting common ownership or infrastructure
  • PTR records - The official reverse DNS entry configured by the IP owner
  • Domain rankings - Majestic and Tranco rankings for hosted domains

Security Applications

Shared hosting creates shared risk. If one site on a server is compromised, attackers may pivot to others. Reverse DNS lookup identifies your hosting neighbors.

For threat investigation, finding all domains on a suspicious IP reveals the scope of malicious infrastructure. Attackers often host multiple phishing sites or malware distribution points on single servers.

Technical Verification

Mail servers require matching forward and reverse DNS. If your MX record points to 192.0.2.1, that IP's PTR record should resolve back to your mail hostname. Reverse DNS lookup verifies this configuration.

Load balancers and CDNs complicate reverse DNS. An IP behind Cloudflare or AWS ELB will show many domains - this is expected behavior, not necessarily shared hosting.

Reverse Lookup by DNS Record Type

DNS Ninja supports multiple reverse lookup modes:

By IP address - Find all hostnames with A or AAAA records pointing to an IP

By nameserver - Find all domains delegated to a specific nameserver

By mail server - Find all domains using a specific MX host

By any DNS value - Search across all record types for any value

Each reverse lookup mode also shows historic relationships — domains that previously used a nameserver, mail server, or IP but have since moved. These "Previously NS for", "Previously MX for", and "Previously A record for" sections appear below the current tables when historic data is available.

Using Reverse DNS Data

Enter an IP address to see all hostnames pointing to it. Results are sorted by relevance, with PTR records and high-traffic domains prioritized.

Click any domain to see its complete DNS configuration. This bidirectional exploration - IP to domains, domains back to IPs - maps infrastructure comprehensively.

→ Find domains on an IP via robtex.com

FAQ

Why do some IPs show thousands of domains?
This indicates shared hosting or a CDN. Many websites can legitimately share infrastructure through hosting providers or content delivery networks.
What's a PTR record?
A PTR (pointer) record is the official reverse DNS entry set by whoever controls the IP address. It's used for mail server verification and network identification.
How is this different from WHOIS?
WHOIS shows IP ownership at the registry level. Reverse DNS shows actual usage - what services and domains actively use that address.
Can websites hide from reverse DNS lookup?
No. If a domain's DNS points to an IP, that relationship is public. There's no way to create a "private" A record.
Can I see historic reverse lookups — domains that previously used a server?
Yes. Below each current reverse lookup table (NS for, MX for, A record for), a "Previously" section shows domains that historically used that nameserver, mail server, or IP but have since moved. This tracks infrastructure migrations and past relationships.