If you’re planning on taking the Security+ exam, you should have a basic understanding of server configuration particularly on how to increase availability between multiple servers.
For example, can you answer this question?
Q. A network administrator configured several servers to work together to increase the processing capabilities for a web application. What does the administrator MOST likely implement?
A. Failover clustering
B. RAID-6
C. EMI shielding
D. Load balancing
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Load Balancers for High Availability
A load balancer can optimize and distribute data loads across multiple computers or multiple networks. For example, if an organization hosts a popular web site, it can use multiple servers hosting the same web site in a web farm. Load-balancing software distributes traffic equally among all the servers in the web farm.
The term load balancer makes it sound like it’s a piece of hardware, but a load balancer can be hardware or software. A hardware-based load balancer accepts traffic and directs it to servers based on factors such as processor utilization and the number of current connections to the server. A software-based load balancer uses software running on each of the servers in the load-balanced cluster to balance the load.
Load balancing primarily provides scalability, but it also contributes to high availability. Scalability refers to the ability of a service to serve more clients without any decrease in performance. Availability ensures that systems are up and operational when needed. By spreading the load among multiple systems, it ensures that individual systems are not overloaded, increasing overall availability.
The 601 Version of the Study Guide
The CompTIA Security+: Get Certified Get Ahead: SY0-601 Study GuideEach of the eleven chapters presents topics in an easy to understand manner and includes real-world examples of security principles in action.
You’ll understand the important and relevant security topics for the Security+ exam, without being overloaded with unnecessary details. Additionally, each chapter includes a comprehensive review section to help you focus on what’s important.
Over 300 realistic practice test questions with in-depth explanations will help you test your comprehension and readiness for the exam. The book includes:
- A 75 question pre-test
- A 75 question post-test
- Practice test questions at the end of every chapter.
Each practice test question includes a detailed explanation to help you understand the content and the reasoning behind the question. You’ll be ready to take and pass the exam the first time you take it.
If you plan to pursue any of the advanced security certifications, this guide will also help you lay a solid foundation of security knowledge. Learn this material, and you’ll be a step ahead for other exams. This SY0-601 study guide is for any IT or security professional interested in advancing in their field, and a must-read for anyone striving to master the basics of IT security.
Consider a web server that can serve 100 clients per minute, but if more than 100 clients connect at a time, performance degrades. You need to either scale up or scale out to serve more clients. You scale the server up by adding additional resources, such as processors and memory, and you scale out by adding additional servers in a load balancer.
The following figure shows an example of a load balancer with multiple web servers. Each web server includes the same web application. Some load balancers simply send new clients to the servers in a round-robin fashion. The load balancer sends the first client to Server 1, the second client to Server 2, and so on. Other load balancers automatically detect the load on individual servers and send new clients to the least used server.
Load balancing
An added benefit of many load balancers is that they can detect when a server fails. If a server stops responding, the load-balancing software no longer sends clients to this server. This contributes to overall high availability for the load balancer.
When servers are load balanced, it’s called a load-balanced cluster, but it is not the same as a failover cluster. A failover cluster provides high availability by ensuring another node can pick up the load for a failed node. A load-balanced cluster provides high availability by sharing the load among multiple servers. When systems must share the same data storage, a failover cluster is appropriate. However, when the systems don’t need to share the same storage, a load-balancing solution is more appropriate, and less expensive. Also, it’s relatively easy to add additional servers to a load-balancing solution.
Remember this
Load balancing increases the overall processing power of a service by sharing the load among multiple servers. Load balancers also ensure availability when a service has an increased number of requests. Failover clusters are one method of server redundancy and they provide high availability for servers. They can remove a server as a single point of failure.
Q. A network administrator configured several servers to work together to increase the processing capabilities for a web application. What does the administrator MOST likely implement?
A. Failover clustering
B. RAID-6
C. EMI shielding
D. Load balancing
Answer is D. The administrator most likely implemented servers to work together in a load-balancing configuration. Load balancing shifts the load between multiple servers to increase the number of clients the application can handle, ultimately increasing the overall processing capabilities.
Failover clustering adds one or more servers for high availability and a redundant array of inexpensive disks 6 (RAID-6) provides fault tolerance for the disk subsystem, but neither increases processing capabilities.
Electromagnetic interference (EMI) shielding is an environmental control that can protect against intermittent problems due to EMI.
