The route I recently went that worked well for the mix of IPv4 addresses and ranges that I had was to, for IPv4 addresses, just use the IP address as a hash key. For IP ranges, I used the first 3 octets of the range as the hash key and the value was a list of ranges that I looped through (it was rare that I had more than one range having the same first three octets). I didn't have any ranges that covered more than one three-octet block, but if I had, I would split such ranges up.

my %hash= (
    '127.0.0.1' => 'localhost',
    '10.11.12.1' => 'router',
    '10.11.12.10' => 'desktop',
    '10.11.12.' => [
        { min => 101, max => 120, desc => 'printers' },
        { min => 250, max => 254, desc => 'tanks' },
    ],
);

sub findIP {
    my( $ip )= @_;
    my $desc= $hash{$ip};
    return( $ip, $desc )
        if  $desc;
    my( $last )=  $ip =~ s/(\d+)$//;
    my $ranges= $hash{$ip};
    for my $range (  @{ $ranges || [] }  ) {
        my( $min, $max )= @$range{'min','max'};
        return( "$ip.$min-$max", $range->{desc} )
            if  $min <= $last  &&  $last <= $max;
    }
    return;
}
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