Use a Schwartzian Transform (ST) or Guttman Rosler Transform (GRT)

ST:

my @domains=qw(
    blah.co.uk
    zzzz.co.uk
    foo.com
    bar.uk.com
    perl.pl
    weirdext.za
    google.de
    google.ca
    google.ru
);

# ST :

my @list=map  { shift @$_ }
         sort { $a->[1] cmp $b->[1] || $a->[0] cmp $b->[0]}
         map  { [ $_, m/(\..*)$/ ] }
         @domains;

print join("\n",@list),"\n\n";

# GRT : (My preference for a variety of reasons, notably speed)

@list=map {substr($_,index($_,"\0")+1)}
      sort
      map  {join ("\0",m/(\..*)$/,$_) }
      @domains;

print join("\n",@list),"\n\n";

# ST : With extra ordering criterion

my %legal=map{ $_ => 1} qw(.co.uk .foo .com .edu);
@list=map  { shift @$_ }
      sort { $b->[2] <=> $a->[2] || $a->[1] cmp $b->[1] || $a->[0] cmp
+ $b->[0]}
      map  { my ($ext)=m/(\..*)$/; [ $_, $ext, $legal{$ext}  ] }
      @domains;

print join("\n",@list),"\n\n";
__END__
Outputs:
----------
google.ca
blah.co.uk
zzzz.co.uk
foo.com
google.de
perl.pl
google.ru
bar.uk.com
weirdext.za

google.ca
blah.co.uk
zzzz.co.uk
foo.com
google.de
perl.pl
google.ru
bar.uk.com
weirdext.za

blah.co.uk
zzzz.co.uk
foo.com
google.ca
google.de
perl.pl
google.ru
bar.uk.com
weirdext.za
[download]

Note I update this node with the extracriterion and a minor typo fix.

Yves / DeMerphq
---
Software Engineering is Programming when you can't. -- E. W. Dijkstra (RIP)
This was my Pentium Post! (686)