Extracting top-level and second-level domain from a URL using regex

Question

How can I extract only top-level and second-level domain from a URL using regex? I want to skip all lower level domains. Any ideas?

Answer 1

If you need to be more specific:

/\.(?:nl|se|no|es|milru|fr|es|uk|ca|de|jp|au|us|ch|it|io|org|com|net|int|edu|mil|arpa)/

Based on http://www.seobythesea.com/2006/01/googles-most-popular-and-least-popular-top-level-domains/