A Sensor network is defined as the critical situational network in which, some critical nodes are defined with energy constraints. To improve the network reliability, such kinds of networks are defined under different coverage methods. These methods includes area coverage, target coverage etc. The area coverage is effective to reduce the chances of orphan nodes under limited sensing range analysis. In same way, target coverage is effective to provide backup to critical nodes. In this work, various issues associated with various coverage methods are explored.