Variable variables are bad, and what you're doing there is dereferencing an array reference, not symbolically dereferencing the value at index 1 of the $prev array as you may have thought. A much better way of dynamically storing the info would be to use a hash to store your data in e.g

my %info = ( ip => '0.0.0.0');
my @list = ();

while (my @prev = $sql->fetchrow_array()){
    $info{ $prev[1] } = $prev[2];
    push @list, { %info };
}

# example usage of created list
print $_->{ip}, "\n" for @list;
[download]

Admittedly this is kinda overkill just to store a list of ip addresses, but it's scales to many keys quite easily. You may even want to use the fetchrow_hashref() for more clarity on what data you're using from the database. Also you'll probably also want to check out info on references, using strict and data structures in perl at the least on your journey to perl mastery.
HTH

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broquaint