my $var =~ m/\w/i;

##</code><code>##

http://www.perlmonks.org/?node=Seekers%20of%20Perl%20Wisdom

##</code><code>##

www.sub.sub2.domain.com
domain.com
ftp.domain.co.uk
adsl-44-33-22-11.dsl.bcvloh.sbcglobal.net

##</code><code>##

gcvloh.sbcglobal.net
sgcglobal.net

##</code><code>##

some.domain.com.au
domain.com.au

##</code><code>##

domain.com
domain.co.uk
domain.fm
domain.name
..etc, etc..

##</code><code>##

 my $d = "spam.yomama.www.zoelife4u.org";
 my @domain = split(/\./, $d);

 my $tld = pop(@domain); #org
 my $baredomain = pop(@domain); #zoelife4u

 my @result = ( $baredomain, $tld );
 $maindomain = join("\.", @result);
 
 print "End: $maindomain\n;"