The technology behind information systems in today’s world has been embedded in nearly every aspect of our lives. Thus, the idea of securing our information systems and/or computer networks has become very paramount. Owing to the significance of computer networks in transporting the information and knowledge generated by the increased diversity and sophistication of computational machinery, it would be very imperative to engage the services of network security professionals to manage the resources that are passed through the various terminals (end points) of the these network, so as to achieve a maximum reliability of the information passed, making sure that this is achieved without creating a discrepancy between the security and usability of such network. This paper examines the various techniques involved in securely maintaining the safe states of an active computer network, its resources and the information it carries. We examined techniques of compromising an information system by breaking into the system without authorised access (Hacking), we also looked at the various phases of digital analysis of an already compromised system, and then we investigated the tools and techniques for digitally analysing a compromised system in other to bring it back to a safe state.