As Necos suggested is better...but if you're having problems dealing with that..it looks as though you're getting standard error output (STDERR) from nslookup intermixing with your script output. Therefore, throw away the STDERR output for the nslookup:

@nsl = `nslookup $_ 2>nul:`;    #for windows
@nsl = `nslookup $_ 2>/dev/null`;    #for unix/linux
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