Wireless Sensor Networks (WSNs) come across various challenges when it comes to its design and operations which cause major degradation in their performance. With increasing number of applications having their own different limitations, make the challenge of application expectations even greater for such resource limited networks. These challenges appear at different layers of WSNs starting from physical layer up to application layer. At routing layer, the main concern of routing protocols is operation of WSN. Thus, the overall performance of WSN, affected by the presence of these challenges, results in major degradation in network's performance. In this paper, to validate the impact of identified challenges from literature review, a mathematical model is presented to calculate the end-to-end delays of a routing protocol ACQUIRE and a comparison is presented between two routing protocols(ACQUIRE and DIRECTED DIFFUSION) for evaluation. On the basis of thorough literature survey carried out for this research and results achieved, recommendations are made for selecting the best protocol depending on nature of application in the presence of considered challenges.