When a domain name or IP address points to a web server, reverse IP domain check looks for other sites that are known to be hosted on the same web server. The information is gleaned from search engine results, which are not guaranteed to be accurate. IP-Address.org has a visually appealing reverse IP lookup tool.
Knowing what other websites are located on a web server is crucial for SEO and web filtering, especially for those on shared web hosting plans.
Reverse IP Lookup is a method of determining whether hostnames have DNS (A) entries linked with an IP address.
Multiple virtual hosts can be served by a web server using a single IP address. In shared hosting situations, this is a common strategy. It’s also typical in many organisations, and it’s a great approach to broaden the attack surface when scouting a web server. If your main target web site appears to be secure, for example, you might be able to obtain access to the underlying operating system by attacking a less secure site on the same server. Potentially circumventing the target site’s security safeguards.