Reverse NS Lookup is a reverse nameserver lookup tool | WhoisXML API

Reverse NS Lookup checks which domains are sharing the same nameserver

Our NS reverse lookup tool lets users retrieve domain name lists sharing a nameserver or hosting company for cybersecurity, marketing, and IT purposes.

Reverse NS Lookup
1,771,916,995Domains and subdomains
196,463,291NS records updated daily
2,131Satisfied customers

Why use our NS reverse lookup tool?

  • Exhaustive and regularly updated data

    Reverse NS Lookup’s outputs are accurate, comprehensive, and backed by the world’s largest DNS record database, with close to 200 million NS records updated every day.

  • Near-instantaneous NS lookup results

    Reverse NS Lookup’s reports are created in a matter of seconds and have shareable URLs for faster communication and decision-making.

Practical usage of a reverse nameserver lookup



  • Gather information about nameservers that have been compromised, added to a blacklist, or used as part of a cyberattack and report the connected domain names to their registrar or hosting company.
  • For each nameserver reported as an indicator of compromise (IoC), Reverse NS Lookup lists down all related domains that should be monitored and possibly added to blocklists.
  • If you are interested in investigating anonymous site visitors whose domains or IP addresses are privacy-protected, but you know their name server, you can do a reverse name server lookup to get to know them better.

SEO and marketing

  • Ensure that your domain doesn’t have a connection to a shady nameserver as that can land you on a blacklist and negatively impact your search engine ranking and brand reputation.
  • Use Reverse NS Lookup to see the latest domain additions to your competitors’ nameserver addresses, which may indicate future product launches and business expansions.
SEO and marketing
IT asset management

IT asset management

  • Study your DNS infrastructure with Reverse NS Lookup to understand which of your domain names are sharing a nameserver and decide whether to keep or change this setup.
  • Examine third parties’ nameserver addresses to gather a list of all domain name assets or map connections following a merger, acquisition, or partnership.
  • Dig deeper into the domains you’re sharing nameservers with to avoid bad online neighbors.
DNS Database Download

Complement nameserver data with information from the largest IP/DNS database

Uncover all historical associations between IP addresses and domains or subdomains. Our data is well-parsed and complete with timestamps for 2 billion hostnames.

Order database
Have questions?

We are here to listen. For a quick response, please select your request type or check our Contact us page for more information. By submitting a request, you agree to our Terms of Service and Privacy Policy.

Or shoot us an email to