#!/usr/bin/perl
use strict;
use warnings;

my @hosts = ("10.10.1.2   # some comment ...\n", 
             "#10.10.1.56\n", 
             "14.1.2.89\n");
             
my $pattern = '10.10.1';            

foreach my $line (@hosts)
{
  if ( my ($comment, $rest) = $line =~ /^(#)?($pattern.*\n)/)
   {
      if (defined $comment)
      {
         $line = $rest;   # delete the beginning # comment char
      }
      else
      {
        $line = "#$rest"; # add a beginning # comment char  
      }
   }
}
print @hosts;
__END__

#10.10.1.2   # some comment ...
10.10.1.56
14.1.2.89