Dear Monks,
What is the meaning of exchange key in this module? For example in this code 
use strict;
use Data::Dumper;
#########################################
die "INPUT: domain:\n" if (@ARGV != 1);
my $domain = $ARGV[0];
#########################################
# Use your own resolver object.
use Net::DNS;
my $res = Net::DNS::Resolver->new;
my  @mx = mx($res, $domain);
print Dumper (@mx);

[download]
for domain yahoo.com I am getting 3 records: 
'exchange' => 'mta7.am0.yahoodns.net'
'exchange' => 'mta5.am0.yahoodns.net'
'exchange' => 'mta6.am0.yahoodns.net'

[download]


this is related to my question in http://www.perlmonks.org/?node_id=929571

In reply to exchange in Net::DNS by vit

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.