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

my @array = (
    'Dut No',
    'asdf',
    'asdf',
    'asdf',
    'Dut No',
    'yxcv',
    'yxcv',
    'yxcv',
    'yxcv',
    'Dut No',
    'fhgj',
    'fhgj',
    'fhgj');

my $count   = 0;
my $in_dut_no   = undef;
foreach my $item (@array){
    if ($item eq "Dut No"){
        $in_dut_no  = 1;
        $count++;
        print "\nDut No ($count)\n";
    }
    elsif ($in_dut_no){
        print "$item\n";
    }
}