I figured the question about getting the ID from the UDP payload with everyone's help. My problem was the implementation of NetPacket::IP and then NetPacket::UDP. The following code gets the ID out of the DNS packet.

my $ip_obj = NetPacket::IP::strip($Raw_IP_Packet);
my $udp_obj = NetPacket::UDP->decode($ip_obj);
if ($udp_obj->{len}) {
 my $payload = $udp_obj->{data};
 my $transid1 = unpack('n', substr($payload,0,2));
 print "The transID is $transid1 \n";
 }
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My big mistake was the first line was wrong. " ...NetPacket::IP->decode($Raw_IP_packet);" This doesn't get the packet set up right. As the documentation for NetPacket::IP says, it happily parses garbage.

Net::DNS::Packet works, but I didn't see the errors of my ways until I got the ID working. the following code works in my situation.

use Net::DNS::Packet;
use Data::Dumper;
use NetPacket::UDP;
use NetPacket::IP;

my $ip_obj = NetPacket::IP::strip($Raw_IP_Packet);
my $udp_obj = NetPacket::UDP->decode($ip_obj);
 if ($udp_obj->{len}) {
     my $payload2 = $udp_obj->{data};
     my $test = Net::DNS::Packet->new(\$payload2);
      if ($test) {
            my @answer = $test->answer;
            print Dumper(@answer);
         } else {
            print "no Net::DNS::Packet \n";}
           }

 }
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I get a complete @answer back when doing "dig slashdot.org" in another terminal.

A big thank you to everyone who gave me a push in the right direction despite my vague question.