What it means
Each IK step corresponds to a specified impact energy, applied with a defined hammer or falling mass. IK10, the highest level, is 20 J, the equivalent of a 5 kg mass dropped from 40 cm. IK08 is 5 J. The rating says the enclosure keeps its protection after the impacts. It does not say the lens window will stay clear of scratches.
How it applies in India
Cameras mounted low, at gates, parking entries, toll booths and junction poles, are within reach of vandals, stones and vehicles. Gantry cameras are usually out of reach and need IK ratings less. For low mounts, IK10 is a common requirement. Specify the IK rating together with the IP rating, because a cracked housing loses its water protection.