my $name = qr/(\w[\w-]*\w?)/;      # any valid hostname segment
my $nnam = qr/(($name\.)*$name)/;  # one or more "name" segments

my @domainnames = (
  qr/$nname\.com/ => 'a commercial domain',
  qr/$nname\.edu/ => 'an educational institution',
);

my %domainnames;
foreach (0 .. @domainnames/2-1) {
   $domainnames{$domainnames[$_*2+0]} = {
      re   => $domainnames[$_*2+0],
      desc => $domainnames[$_*2+1],
   };
}