Not really sure why it doesn't get past the '|' (works fine here), but what looks suspicious is the @nodes=(<LIST>); as this reads everything from the second line onwards into an array which you never use in the loop. As a result, there would only be one call to nslookup with $_ holding the first line of the input file. Not sure if that's intended.

Independently of that, you probably want to escape the $2 in the awk command, because backticks do interpolate variables... i.e.

my $nodename=`nslookup $_ | awk -F Name: '{ print \$2 }'`;
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