I don't know how you populate your hash, but you wouldn't need to sort at all if you used an array instead:

my @SRV = (
  'zumen530n.pdg.duranto.com',
  'zumen531n.pdg.duranto.com',
  'zumen532n.pdg.duranto.com', # etc
);
print "$_ $SRV[ $_ ]\n" for 0 .. $#SRV;
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Of course, this prints 0-20 instead of 1-21, but that's easy to fix if it's important.

Update: In fact, whenever I see a hash like:

my %h = (
  1 => 'foo',
  2 => 'bar',
  3 => 'baz',
  4 => 'quux',
);
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I always consider whether it wouldn't be better to use a simple array.