Certified: The Security+ Prepcast

In this episode, we’re exploring high availability architectures. High availability—often abbreviated as H A—is a foundational concept in both cybersecurity and system design. It ensures that services remain accessible even during failures, maintenance, or unexpected traffic surges. But designing for availability also comes with security trade-offs. Let’s look at how high availability works, why it matters, and how to secure it effectively without compromising performance.
Let’s start with the basics. High availability means designing systems so they remain operational and accessible as close to one hundred percent of the time as possible. This doesn’t mean systems are invulnerable to failure—but rather that failures are anticipated and mitigated through redundancy, fault tolerance, and rapid recovery.
One common high availability technique is clustering. In a clustered environment, multiple systems—called nodes—work together to provide a shared service. If one node fails, the others take over automatically. This might apply to file servers, databases, or web services. The transition is often seamless to users, and downtime is minimized or eliminated.
Another popular approach is load balancing. Load balancers distribute incoming traffic across multiple servers or instances. This not only improves performance and scalability, but also ensures that if one server goes offline, traffic is automatically redirected to healthy systems. Load balancers can be hardware devices, virtual appliances, or cloud-native services.
Redundancy also plays a key role. This includes having backup hardware, secondary data paths, redundant power supplies, and mirrored databases. When one element fails, another is ready to take over. Redundancy ensures that single points of failure don’t result in a complete outage.
Now let’s talk about why high availability matters to security. From a cybersecurity perspective, availability is one of the three pillars of the confidentiality, integrity, and availability triad. It’s not just about keeping services running—it’s about ensuring that users can access systems when they need them, even under attack or during unexpected failures.
Security controls must support high availability without interfering with it. For example, if a firewall is configured without redundancy and it fails, it could take down an entire network segment. The same is true for identity services—if authentication servers are not fault-tolerant, users could be locked out of systems during a failure. A denial-of-service condition doesn’t always come from a hacker. Sometimes it’s a misconfigured security appliance or a failure to design for failover.
One challenge in high availability architecture is striking the right balance between resilience and security. Systems must be accessible and responsive, but they must also be protected from unauthorized access and abuse. Too much security friction—like aggressive timeouts or excessive authentication prompts—can hinder availability. On the other hand, relaxing security policies to improve user experience may open the door to attacks.
To manage this balance, high availability environments should include layered defenses. Firewalls, intrusion detection, and access controls must be redundant and fault-tolerant. Monitoring tools must be able to distinguish between normal failover behavior and signs of attack. And security policies must be applied consistently across all nodes and systems—so that no matter which server a user connects to, the security posture remains the same.
Let’s look at a real-world example. A national retailer experienced a surge in traffic during a seasonal promotion. Their load balancers were properly configured to handle the volume, but a misconfigured web application firewall created a bottleneck under load. The firewall began dropping legitimate connections, resulting in lost sales and a flood of support calls. The problem wasn’t the volume of traffic—it was the failure of a critical security component to scale with the rest of the infrastructure. After the incident, the organization implemented redundant firewall nodes with load balancing and tested them under load conditions.
Another case involved a healthcare provider whose patient portal relied on a single authentication server. When the server went down for maintenance, no one could access the system. This included both patients and clinicians. As a result, care was delayed, and patient trust was impacted. The solution was to deploy multiple authentication servers in a failover configuration, along with a monitoring system to detect failures and automatically reroute traffic.
As you prepare for the Security Plus exam, understand that high availability is about more than uptime—it’s about maintaining secure, functional access in the face of failures, attacks, or misconfigurations. You may be asked to identify the role of clustering, load balancing, or redundant paths in supporting availability. Be ready to explain how high availability supports the security triad and how to avoid introducing single points of failure in critical services. You may also encounter questions where a security tool causes an outage, and your job is to recommend a solution that preserves both availability and protection.