Description: The article describes the features of models of functioning web-based system. For a ternary system structure it’s proposed simulation model that takes into account the change in the flow parameter attacks on service availability DNS. Peculiarities of simulation models are described; the convergence of the results with an analytical model is analyzed. Conclusions about the possibility of using simulation models in determining the optimal variant of audits and update the security features of the system during its application have been done.
Keywords: simulation model, service-oriented web-system, attack on the availability of services