Tanvi, cracking almost always comes down to one of four things, and Vikram's advice to isolate one variable at a time is the correct method.
One, oven temperature running hot — the most common cause by a distance, and the easiest to rule out with a cheap oven thermometer. Two, under-developed macaronage, as Ananya describes: air that has not been worked out has to escape, and it exits through the weakest point. Three, insufficient skin formation before baking. In humid Indian conditions the standard resting times in most European recipes are simply too short; you want a shell that is genuinely dry to a light touch, and that can take considerably longer here. Four, an under-stable meringue, usually from adding sugar too fast or from any trace of fat in the bowl.
Rule them out in that order. Thermometer first, because if the oven is lying to you every other adjustment you make is noise.
One note specific to baking in India: humidity affects both the resting stage and the meringue, and it varies enormously by city and season. A recipe that works reliably in a dry month may need a longer rest in a wet one. That is not you doing something wrong.
