Do you know how redundancy provides fault tolerance? You should if you plan to take the Security+ exam. Redundancy adds duplication to critical system components and networks. This post should help.
Redundancy into Systems and Networks
One of the constants with computers, subsystems, and networks is that they will fail. It’s one of the few things you can count on. It’s not a matter of if they will fail, but when. However, by adding redundancy into your systems and networks, you can increase the reliability of your systems even when they fail. By increasing reliability, you increase one of the core security goals: availability.

Redundancy adds duplication to critical system components and networks and provides fault tolerance. If a critical component has a fault, the duplication provided by the redundancy allows the service to continue as if a fault never occurred. In other words, a system with fault tolerance can suffer a fault, but it can tolerate it and continue to operate. Organizations often add redundancies to eliminate single points of failure.
You can add redundancies at multiple levels:
- Disk redundancies using RAID
- Server redundancies by adding failover clusters
- Power redundancies by adding generators or a UPS
- Site redundancies by adding hot, cold, or warm sites
Redundancy to Eliminate Single Point of Failure
A single point of failure is a component within a system that can cause the entire system to fail if the component fails. When designing redundancies, an organization will examine different components to determine if they are a single point of failure. If so, they take steps to provide a redundancy or fault-tolerance capability. The goal is to increase reliability and availability of the systems.
Some examples of single points of failure include:
- If a server uses a single drive, the system will crash if the single drive fails. Redundant array of inexpensive disks (RAID) provides fault tolerance for hard drives and is a relatively inexpensive method of adding fault tolerance to a system.
- If a server provides a critical service and its failure halts the service, it is a single point of failure. Failover clusters provide fault tolerance for critical servers.
- If an organization only has one source of power for critical systems, the power is a single point of failure. However, elements such as uninterruptible power supplies (UPSs) and power generators provide fault tolerance for power outages.
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The
CompTIA Security+: Get Certified Get Ahead: SY0-501 Study Guide
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Although information technology (IT) personnel recognize the risks with single points of failure, they often overlook them until a disaster occurs. However, tools such as business continuity plans help an organization identify critical services and address single points of failure.
Remember this
A single point of failure is any component whose failure results in the failure of an entire system. Elements such as RAID, failover clustering, UPSs, and generators remove many single points of failure. RAID is an inexpensive method used to add fault tolerance and increase availability.
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RAID and Security+ (RAID-6, 10)
Security+ Disaster Recovery
Security+ Practice Test Questions
SY0-501 Practice Test Questions
Over 300 realistic Security+ practice test questions
All questions include explanations so you’ll know why the correct answers are correct,
and why the incorrect answers are incorrect.
Pass the Security+ Exam
the First Time You Take It
Multiple quiz formats to let you use these questions based on the way you learn.
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- Test mode – randomized. View each of the questions in random order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
- Test mode – not randomized. View each of the questions in the same order. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
- Test mode – 75 random questions. View 75 random questions from the full test bank similar to how the Security+ exam has a potential maximum of 75 multiple choice questions. In test mode, you can only see the correct answers and explanations after you complete the test. Click here to see how test mode works.
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SY0-501 Practice Test Questions
INCLUDES QUESTIONS TO HELP YOU PREPARE
FOR THE NEW PERFORMANCE BASED QUESTIONS
Bonus – Performance Based Questions
Three sets of performance-based questions including over 30 questions. These questions show you what you can expect in the live exam. They include drag and drop, matching, sorting, and fill in the blank questions. See a
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New multiple-choice questions in the extra test bank. Questions are added occasionally. You can see what has been added recently
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Get the full bank of Security+ (SYO-501) Practice Test Questions Here
Get the full bank of Security+ Practice Test Questions
Click here if you’re looking for SY0-501 Full Study Package
See Chapter 9 of the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide for more information on redundancy.