- [Instructor] As a security professional,
you must also understand how to apply security controls
that protect the availability of information in systems.
As the third leg of the CIA tirade,
availability controls ensure that information and systems
remain available to authorized users when needed.
Availability controls protect against disruptions
to normal system operation, or data availability.
Potential availability failures may result
from a variety of causes, such as malicious attackers,
like someone conducting a denial-of-service attack
to bring down a website.
Or component failures,
such as the failure of a hard drive or power supply.
They can also come from application failures,
such as errors in code that cause an application crash.
Or utility failures, such as a power outage
that disrupts systems, or a network disruption
that prevents internet access.
There are many controls in place
that can protect the availability
of systems and information.
One example of an availability control
is the use of redundant components
such as including two power supplies in a system,
or having extra hard drives that use RAID technology.
Another example is the use of high availability systems
that have multiple servers dedicated to the same purpose,
so that if one server fails,
the others may continue carrying the operational load.
And the more general category of fault tolerance,
ensures that IT services remain functioning,
even when small failures occur.
There is one additional availability control
that you should be familiar with for the CISSP exam.
Keeping operating systems and applications patched
to current levels, ensures that any flaws
identified by the manufacturer are corrected promptly.
This not only protects your system from vulnerabilities
that might allow an attacker to gain access,
but also corrects issues that may cause
the system to crash, disrupting availability.