hello monks

I' m in fix with the below code (that is a simplified version of my code, only to show the problem, thaks to wfsp). 

use warnings;
use strict;
use Data::Dumper;

my @temp;
$temp[12] = q{one two three };

my %hash = (
 alias => { map {$_ => risolve( $_ );} split / /,$temp[12] },
);

sub risolve{
    my $host = shift;
    open DNS, "ping -l o -n 1 $host >nil|"||die;
    while (<DNS>) {1}               ### COMMENT THIS LINE AND IT WORKS
    close DNS;
    return q{four five six};
}

print Dumper \%hash;

[download]
if run as is it prints: 
$VAR1 = {
          'alias' => {
                       '' => 'four five six'
                     }
        };

[download]
and it warns
Use of uninitialized value in anonymous hash ({}) at wsfp-scratchpad2.
+pl line 11.
Use of uninitialized value in anonymous hash ({}) at wsfp-scratchpad2.
+pl line 11.
Use of uninitialized value in anonymous hash ({}) at wsfp-scratchpad2.
+pl line 11.

[download]
but if you comment out the line while (<DNS>) {1} it prints as expected:
$VAR1 = {
          'alias' => {
                       'three' => 'four five six',
                       'one' => 'four five six',
                       'two' => 'four five six'
                     }
        };

[download]
what is happening?
thanks in advance
Lor*

In reply to problem with $ARG by Discipulus

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.