Find subdomains is 1 step collect information in hacking, if not pay attention, the website sharing vulnerable when the hacker sharing find ways to attack and the subdomain is of little interest and attention during the website development.
In addition you can discover more of the features amazing of this website in collecting website information such as: Google Hacking, Web Server Vulnerability Scan with Nikto, Find VHosts, TCP Port Scan, WordPress Scan, Whois Lookup.
Of course a number of advanced functions you have to buy Credits new can check.
Use type site:domain to search engines to find subdomain
You type type the following: site:ten+domain (for example: site:thuthuatvip.com ) to the search engine search help you, more often it sharing find out if the subdomain is index, however this doesn't work, scan tool above.
DNS Dumpster | this tool developed by hackertarget.com and is tool that helps find DNS of website that I use most often because it's analysis is quite deep, find the correct DNS get familiar with diagrams intuitive for the viewer.