Darren Chamberlain > Net-Nslookup > Net::Nslookup



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Module Version: 2.04   Source  


Net::Nslookup - Provide nslookup(1)-like capabilities


  use Net::Nslookup;
  my @addrs = nslookup $host;

  my @mx = nslookup(type => "MX", domain => "perl.org");


Net::Nslookup provides the capabilities of the standard UNIX command line tool nslookup(1). Net::DNS is a wonderful and full featured module, but quite often, all you need is `nslookup $host`. This module provides that functionality.

Net::Nslookup exports a single function, called nslookup. nslookup can be used to retrieve A, PTR, CNAME, MX, NS, SOA, TXT, and SRV records.

  my $a  = nslookup(host => "use.perl.org", type => "A");

  my @mx = nslookup(domain => "perl.org", type => "MX");

  my @ns = nslookup(domain => "perl.org", type => "NS");

  my $name = nslookup(host => "", type => "PTR");

  my @srv = nslookup(term => "_jabber._tcp.gmail.com", type => "SRV");

nslookup takes a hash of options, one of which should be term, and performs a DNS lookup on that term. The type of lookup is determined by the type argument. If server is specified (it should be an IP address, or a reference to an array of IP addresses), that server(s) will be used for lookups.

If only a single argument is passed in, the type defaults to A, that is, a normal A record lookup.

If nslookup is called in a list context, and there is more than one address, an array is returned. If nslookup is called in a scalar context, and there is more than one address, nslookup returns the first address. If there is only one address returned, then, naturally, it will be the only one returned, regardless of the calling context.

domain and host are synonyms for term, and can be used to make client code more readable. For example, use domain when getting NS records, and use host for A records; both do the same thing.

server should be a single IP address or a reference to an array of IP addresses:

  my @a = nslookup(host => 'example.com', server => '');

  my @a = nslookup(host => 'example.com', server => [ '', '' ])

By default, when doing CNAME, MX, and NS lookups, nslookup returns names, not addresses. This is a change from versions prior to 2.0, which always tried to resolve names to addresses. Pass the recurse => 1 flag to nslookup to have it follow CNAME, MX, and NS lookups. Note that this usage of "recurse" is not consistent with the official DNS meaning of recurse.

    # returns soemthing like ("mail.example.com")
    my @mx = nslookup(domain => 'example.com', type => 'MX');

    # returns soemthing like ("")
    my @mx = nslookup(domain => 'example.com', type => 'MX', recurse => 1);

SOA lookups return the SOA record in the same format as the `host` tool:

    print nslookup(domain => 'example.com', type => 'SOA');
    dns1.icann.org. hostmaster.icann.org. 2011061433 7200 3600 1209600 3600


Lookups timeout after 15 seconds by default, but this can be configured by passing timeout => X to nslookup.


Pass debug => 1 to nslookup to emit debugging messages to STDERR.


darren chamberlain <darren@cpan.org>

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