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

Reverse NS Lookup: Determine which domains share the same name server

Get a list of domain names that share a name server for cybersecurity, marketing, and IT purposes. Test our Reverse NS Lookup now. Download our product sheet to learn more.

32 Billion+Domains and subdomains
BillionsNS records
52,000+Satisfied customers
14+Years of data crawling

What is a reverse nameserver lookup?

A reverse nameserver lookup, also referred to as a reverse NS lookup, is a search for all of the domain names that share a nameserver specified as a search term. A reverse namerserver lookup allows to understand if a nameserver is dedicated or shared among several hosts.

Why use our NS reverse lookup tool?

  • Exhaustive and regularly updated data

    Reverse NS Lookup’s outputs are accurate, comprehensive, and backed by our large DNS record database, with millions NS records updated every week.

  • 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.

Frequently Asked Questions

  • What are NS records?

    An NS record specifies what DNS server is responsible for a given domain. It tells you which NS contains the actual DNS records of the domain of interest. In even simpler terms, an NS record tells Internet-connected systems where to go to find out what IP address corresponds to a specific domain.

  • Why should NS records be properly managed?

    NS record management is important as failure to do so can result in non-resolution (i.e., users can’t find your website). NS records must always be updated as well to ensure they point to the right pages. Threat actors may also try making unauthorized changes to these records to redirect your site visitors to malicious pages.

  • Are NS records and DNS zones connected?

    Yes, definitely. NS records can be used to identify your DNS zone. A DNS zone is that unique part of the DNS where your domain resides that is administered by a single manager. That manager could be a person, an organization, or a company who/that is responsible for maintaining the zone by maintaining control of its components, primarily authoritative NSs.

DNS Database Download

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

Uncover all historical associations between NS or other DNS records and domains or subdomains. Our data is well-parsed and complete with timestamps.

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