Abstract
This article examines the issue of enhancing the reliability of information systems. As a solution to this problem, an approach to assessing resilience to failures in data exchange systems is presented, based on the use of mathematical analysis methods for systems capable of operating at three levels. The developed mathematical model is represented in the form of a graph of states and failure probabilities, as well as a complex of differential equations for its description. The solution of the proposed model allows determining the probabilities of failures at different stages of the information systems' operation. This, in turn, contributes to the effective identification and elimination of malfunctions and equipment failures.