Internet of Things (IoT) has emerged as a revolutionary technology that has become an integral part of smart cities. It has numerous, longstanding, economical and safety-critical smart city applications. Data acquisition for IoT applications requires sensor networks. Reliability, Resilience, and Energy conservation are the three most critical wireless sensor requirements. Fault tolerance ensures the reliability and the resilience of the sensor network in case of failures. In this paper, we propose a new taxonomy for fault tolerant technique for wireless sensor networks deployed in an IoT environment, and qualitatively compare some major existing methods and propose a new fault-tolerant routing technique for hierarchical sensor networks. The algorithm is a heterogeneous technique based on Dynamic source routing (DSR), vice cluster heads, energy thresholding and hierarchical sensor networks. The proposed technique was simulated and is compared with current techniques to evaluate its validity and performance.