Given recent events, training during quarantine can only take place remotely. To ensure quality training, communication must be seamless. To do this, the network must function smoothly. The solution to this problem is functionally stable networks that allow uninterrupted transmission of information due to redundancy. An important issue is the definition of redundancy. To solve this problem, the article considers the method of synthesis of the structure of the distance learning system. The method of synthesis of network structure used for providing distance learning by the criterion of maximum functional stability on the basis of the introduction of correcting communication lines is offered. With this method, you can develop tools for self-recovery of distributed software, taking into account the characteristics of disparate computer resources through the use of redundancy. This will allow you to develop functionally stable software systems, significantly reduce the recovery time of such systems after or in the event of possible failures. To increase the efficiency of the developed method, the mathematical model of the hyper network based on two hypergraphs was improved, which allows taking into account different requirements for the quality of the network.

The current pace of development of information technology has created the preconditions for the emergence of a wide range of tools for providing educational services using distance learning technologies. This is confirmed by the intensification of the use of distance learning systems in the conditions of sanitary and epidemiological restrictions and the need for acute cost savings.
The existing scientific and methodological apparatus for studying the quality of functioning of distance learning systems is mostly based on approaches to separate assessment of the effectiveness of their elements and the relevant quality indicators. This limits the ability to take into account important factors in the decision-making process and requires comprehensive consideration of the contributions of relevant subsystems to the functioning of the distance learning system.
In order to solve this problem, the article presents a comprehensive methodology for assessing the effectiveness of distance learning system, based on methods of probability theory and hierarchy analysis and describes the patterns of influence on the effectiveness of distance learning system of importance and contributions of its subsystems. Comparative analysis of the data obtained by monitoring and forecasting performance indicators based on the proposed method, shows an increase in the reliability of the assessment within 15-18%, which in contrast to the existing reduction of standard deviation of performance indicators by an average of 26% and ensures the adequacy of the results within certain assumptions and hypotheses.
In such conditions, the choice of an appropriate option for the construction of the DN system is ensured by the reliability of the forecast of the results of its operation in the range of 82-85%, which is high enough to make appropriate decisions.
The value of this study lies in the possibility of using the tested scientific and methodological apparatus in forecasting the outcome of the system and saving material, financial and human resources in the process of implementing the relevant recommendations in practice. This fact makes it possible to eliminate limitations in the practice of building distance learning systems and creates a new opportunity to cover a wider range of factors that affect the quality of operation.The application of this technique makes it possible to predict the results of the joint operation of the relevant subsystems of the distance learning system, taking into account their contribution to the overall result.

The paper describes the organization of the unified information space which is based on the uniform principles and the general rules that ensure the informational interaction of objects.
In practice, in case when the communication with an information object of the unified information space is lost, the necessary information about this object should be collected by the analysis of previous interactions of the information object with the other information objects. The goal of this paper article is to develop a mechanism that will allow restore the missing parameters of information objects in case of communication loss with this object.
There was performed the experimental researches with the proposed mechanisms. The experiments have shown that there is an unequivocal relationship between the quality of restoration of an information object and the topology of links within an unified information space.

A concept targeting information technology is considered. The model of selection of the optimal amount of advertising on various Internet resources, in order to maximize the desired reach to the target audience is analyzed which. This model is different from traditional. A chance constrained target programming model was developed after considering the parameter that corresponds to reach for different media as random variables. The random variables in this case has been considered as the values with known mean and standard deviation. The reachability parameter can be determined by finding the ideal solution and the law on which the parameter values change. The method of multicriteria optimization is examined with determination of resulting objective function, which allows to consider various aspects of the problems of media choice and optimal budgeting and budget allocation simultaneously to get a satisfactory solution of the problem.

A concept software-defined network is considered. Architecture of software-defined network is analyzed which, differently from traditional, foresee the separation of C-plane from a plane communication of data. The method of multicriterion optimization of multilevel networks is examined with determination of resulting objective function, which allows to carry out the synthesis of control system software-defined network (SDN) in the conditions of unforeseen changes of structure of the system.

The article deals with the issues of the security of distributed and scalable computer systems based on the risk-based approach. The main existing methods for predicting the consequences of the dangerous actions of the intrusion agents are described. There is shown a generalized structural scheme of job manager in the context of a risk-based approach. Suggested analytical assessments for the security risk level in the distributed computer systems allow performing the critical time values forecast for the situation analysis and decision-making for the current configuration of a distributed computer system. These assessments are based on the number of used nodes and data links channels, the number of active security and monitoring mechanisms at the current period, as well as on the intensity of the security threats realization and on the activation intensity of the intrusion prevention mechanisms. The proposed comprehensive analytical risks assessments allow analyzing the dynamics of intrusions processes, the dynamics of the security level recovery and the corresponding dynamics of the risks level in the distributed computer system.