tld of example.com is .com
tld of example.co.uk is .co.uk
tld of example.com.cn is .com.cn
tld of example.abc.cn is .cn, not abc.cn
it seems the browser know it when setting cookie with domain name (reject to save cookie into tld), but what if there's a new tld? how can a browser know it without update/patch? is there any pattern to recognize which part is tld without knowing a list a tld?