This is a site specific question. If the range is far from surrounding structures and there are no safety hazards on either side (or at the rear), then you might not need netting and poles. However, this is almost never the case. In 25 years we have yet to work on a range project that did not have some netting requirement. Because good sites often have a high land cost, it is almost a universal rule that you will need some netting. To contain all golf balls in your range, the ball flight graphs from Wilson and Spalding show a maximum height of 110′ for all clubs (9 iron to driver).