sub server_sort {
  # bi-valued key = 0 if {tag} is not 53 and 1 if {tag} is 53
  (($my_server_hash{$a}{tag} == 53)
   <=>
   ($my_server_hash{$b}{tag} == 53))
  ||
  $a cmp $b
  ||
  $my_server_hash{$a}{tag} <=> $my_server_hash{$b}{tag}
}

my @server_names = sort &server_sort keys %my_server_hash;

# now the server names are sorted with the 53 tags grouped
# separately from the rest.