gTLD (Generic Top Level)
eg: .com, .org, .edu
ccTLD (Country Code Top Level)
eg: .in , .co.uk , .ca
sits on the left side of domain.
in admin.tryhackme.com the admin part is the subdomain.
there is no limit to subdomain that u can make for a domain.
same creation restriction as second level domain (63 characters.)
The Maximum length of a domain should be less than 253.