myhost.example.com.----> Fully Qualified Domain Name
myhost----> is the host located within domain example.com (subdomain)
admin.example.comis not a valid subdomain of root domain
example.comThere may be web services hosted on them but not on the default ports(80/443). Also, there may be some other vulnerable services running on the subdomain whose exploits are publicly available. So in such a case, it's always better that you DNS resolve the subdomain rather than directly web probing them.