I found a tool to know the domain that hosts a seridor. It is useful to know, for example, how congested is a shared hosting. So far there were tools of this type but were all paid.
http://www.yougetsignal.com/tools/web-sites-on-web-server/
On the website we read: "This tool takes the IP web server that hosts the domain and find other sites hosted on the same server. The information is taken from results of search tools, which is not guaranteed to be complete information. Knowing that other sites host a server is important both for SEO and web filtering, particularly for those servers that are hosted on shared hosting plans "
