whois.domaintools.comは安全ですか？

Taken from their Web site: DomainTools is the leader in domain name, DNS and Internet OSINT-based cyber threat intelligence and cybercrime forensics products and data. With over 14 years of domain name, DNS and related ‘cyber fingerprint’ data across the global Internet, DomainTools helps companies assess security threat risks, profile attackers, investigate online fraud and crimes, and map cyber activity in order to stop attacks. Be wary of clicking on any of the ads on the site. Some of these are connected to known malware sites and might result in the download of unwanted pups onto the visitors system Uses Captcha to prevent use by bots. Good array of investigatory tools.

The BEST place to get DOMAIN NAME Owner (Who is) , DNS , IP ADDRESS, etc. The basic "free" (registered member) membership allows you to obtain quite a bit more information than those who do not register. There are "premium" (paid) services for the professionals who really need it but for the average person there is no need for them.