The performance evaluation of complex networks which are highly mobile with arbitrary topology in terms of reliability is an important fundamental problem of mobile ad hoc networks. The issue is challenging with a resilient number of failed nodes; caused due to several reasons, viz., technical failures, power limitations, storage capacity, fast mobility, node isolations, physical obstacles, atmospheric effects, congestion, low energy levels, unpredictable nature that leads to performance degradation of MANET reliability. The node failure has a significant impact on the network connectivity because of the aforementioned reasons. Moreover, the reliability evaluation is an NP-hard problem and, therefore, this paper focuses on a quantitative study and investigates the performance evaluation of MANET in terms of number of failed nodes for different scenario metrics. The validated simulation results using Monte Carlo simulation show the effect of node failure on MANET reliability.