regex match main domain name

Question

I need to be able to identify a domain name of any subdomain.

Examples:

For all of thiese I need to match only example.co / example.com

Answer 1

This will match:

([0-9A-Za-z]{2,}\.[0-9A-Za-z]{2,3}\.[0-9A-Za-z]{2,3}|[0-9A-Za-z]{2,}\.[0-9A-Za-z]{2,3})$

as long as:

1. there're no extra spaces at the end of each line
2. all domain codes used are short, two or three letters long. Wil not work with long domain codes like .info.

Bassically what it does is match any of these two:

1. word two letters or longer:dot:two or three letters word:dot:two or three letters word:end of line
2. word two letters or longer:dot:two or three letters word:end of line

Short version:

(\w{2,}\.\w{2,3}\.\w{2,3}|\w{2,}\.\w{2,3})$

If you want it to only match whole lines, then add ^ at the beginning

This is how I tested it: