This thesis focuses on the configuration of complex computer networks, with a particular emphasis on the use of Cisco Packet Tracer for simulating and testing various network topologies. The paper provides a detailed explanation of key network components, including VLAN configuration, routing, NAT, DHCP, and DNS protocols, as well as their practical applications in real network environments. The goal of the thesis was to explore methods and tools that enable the creation of stable, secure, and scalable networks, and to highlight the importance of proper configuration in achieving optimal network functionality. By using simulations in Cisco Packet Tracer, a better understanding was gained of how theoretical principles are applied in practice and how the configuration of different network elements can impact network performance and security. It was concluded that proper network design and configuration play a crucial role in maintaining business continuity and data protection, and that tools like Cisco Packet Tracer should be regularly used to test and improve network settings before implementation in real environments. This paper also provides guidelines for future students and professionals who wish to expand their knowledge in the field of computer networks.