== Availability

Availability is "the property of being accessible and usable on demand by an authorized entity." In other words, authorized persons should have access to permitted resources at all times.

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=== Examples that compromise availability:

** denial-of-service attacks (DOS)
** hardware failures
** fire or other natural disasters
** software or network misconfigurations

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=== Examples of methods ensuring availability

** intrusion detection systems (IDSs)
** network traffic control
** firewalls
** physical security of hardware and underlying infrastructure
*** protection against fire, water, and other elements
** hardware maintenance
** redundancy
