DaNewf is right. You can (should!!!) start out at some short range in order to get on paper, but even if the trajectory of your load would give you a dead-on elevation at both ranges, ie, 25 and 200 yards, you actually have to confirm your zero by shooting at the longer range. It is entirely possible (LIKELY, EVEN!!) that your windage will have to be changed to get you dead-on at the longer range.

Larry