The Internet of things (IoT) is highly suitable for military, environmental, agricultural, and other remote real-time monitoring applications. A reliable topology ensures a stable and dependable monitoring system. Considering the research of an IoT-based air pollution monitoring system for industrial emissions as background, this study proposes a novel dual redundant node deployment scheme. Specifically, hexagonal clustering is proposed for the internal regions. In addition, relationship and quantification formulas for a monitoring area are presented, and the communication range, total number of layers of the topology, and number of cluster headers are determined. Interruptions in a monitoring system may reduce the quality of IoT services. Therefore, sensor nodes are also deployed around the monitoring area (in outer regions). The basic external area is modeled and proposed as a rectangular, 1-covered isosceles triangle deployment plan with the objective of minimizing the number of sensor nodes. A quantitative formula is given using the sensing radius, width of the rectangle, and adjacent distance between nodes. Reliability is a critical index in IoT-based applications. Thus, the reliability of a hexagonal clustering topology is presented using reliability block diagrams. For a reliable remote transmission model, different redundant systems are implemented. Furthermore, the reliability value and mean time to failures are calculated. The results are later compared and analyzed quantitatively. This study presents important theoretical and application-based knowledge that can guarantee reliable service for an IoT-based monitoring system.