When are you permitted to re-drop a golf ball without penalty?
A dropped ball must be re-dropped, without penalty, if it:
(i) rolls into and comes to rest in a hazard;
(ii) rolls out of and comes to rest outside a hazard;
(iii) rolls onto and comes to rest on a putting green;
(iv) rolls and comes to rest out of bounds;
(v) rolls to and comes to rest in a position where there is interference by the condition from which relief was taken under Rule 24-2b (immovable obstruction), Rule 25-1 (abnormal ground conditions), Rule 25-3 (wrong putting green) or a Local Rule (Rule 33-8a), or rolls back into the pitch-mark from which it was lifted under Rule 25-2 (embedded ball);
(vi) rolls and comes to rest more than two club-lengths from where it first struck a part of the course; or
(vii) rolls and comes to rest nearer the hole than:
(a) its original position or estimated position (see Rule 20-2b) unless otherwise permitted by the Rules; or
(b) the nearest point of relief or maximum available relief (Rule 24-2, 25-1 or 25-3); or
(c) the point where the original ball last crossed the margin of the water hazard or lateral water hazard (Rule 26-1).
If the ball when re-dropped rolls into any position listed above, it must be placed as near as possible to the spot where it first struck a part of the course when re-dropped.
Note 1: If a ball when dropped or re-dropped comes to rest and subsequently moves, the ball must be played as it lies, unless the provisions of any other Rule apply.
Note 2: If a ball to be re-dropped or placed under this Rule is not immediately recoverable, another ball may be substituted.