Availability
For every information system to provide its reason, the information must be existing when it is desirable. This way that the computing systems used to process and store the information, the safety controls used to guard it, and the communication channels used to access it must be functioning properly. High accessibility systems aim to remain accessible at all times, stopping service disruptions due to hardware failures, power outages, and system upgrades. Ensuring accessibility also involves stopping DoS attacks (denial-of- service attacks).
In 2002, Donn Parker planned an alternative model for the classic CIA triad that he called the six atomic elements of information. The rudiments are authenticity, confidentiality, integrity, possession, availability, and utility. The merits of the Parkerian hexad are a topic of debate in the middle of security professionals.