SY0-701 Question 233
Single answerHigh availability: Load balancing vs. clusteringA company hosts a customer-facing web application that must remain available during peak shopping periods. The security team also wants to reduce the impact of denial-of-service conditions by distributing legitimate traffic across multiple web servers. During a design review, an administrator proposes replacing the current active/passive database failover cluster with a load balancer so all systems can share the traffic load. Which solution best meets the company's availability and security goals?
- A
Deploy a load balancer in front of multiple web servers, and keep the database on a failover cluster
- B
Replace both the web tier and the database tier with a single active/active load-balanced server pair
- C
Use only a database cluster because clustering provides the same traffic distribution benefits as load balancing
- D
Place the database servers behind the load balancer and remove clustering to simplify failover
Show answer and explanation
Correct answer: A
Explanation
The key distinction is that load balancing and clustering solve different availability problems. Load balancing spreads requests across multiple systems to improve performance, scalability, and availability at tiers such as web or application servers. Clustering is designed to provide redundancy and failover for services that must remain available even when a node fails, especially stateful services such as databases. In security operations, load balancing can also help reduce the impact of traffic surges by distributing requests, though it is not a substitute for dedicated DDoS protections. Best-practice architecture commonly uses load balancers for front-end services and clustering or other failover technologies for back-end data services. This aligns with standard vendor guidance from major platform and infrastructure providers, which distinguish traffic distribution functions from failover and state-management functions.
- A. Correct.
Correct. Load balancing is appropriate for the web tier because it distributes client requests across multiple servers, improving scalability and availability while helping absorb spikes in legitimate traffic. A failover cluster remains appropriate for the database tier because databases often require coordinated state, transaction integrity, and controlled failover rather than simple request distribution. This design matches real-world best practice: use load balancing for stateless or horizontally scaled services, and clustering for stateful back-end services that need redundancy and failover.
- B. Incorrect.
Incorrect. While active/active designs exist for some applications, a 'single active/active load-balanced server pair' does not appropriately replace a traditional database failover cluster in most Security+ level scenarios. Load balancers do not provide the same protections for database consistency, locking, replication state, or failover orchestration that clustering technologies are designed to handle. This option reflects the common misconception that load balancing and clustering are interchangeable.
- C. Incorrect.
Incorrect. Clustering and load balancing serve different purposes. A database cluster can improve availability through node redundancy and failover, but it does not inherently distribute incoming web traffic the way a load balancer does. Someone might choose this option by assuming any high-availability technology provides the same benefit, but traffic distribution across multiple web servers is specifically a load-balancing function.
- D. Incorrect.
Incorrect. Placing database servers behind a load balancer does not eliminate the need for clustering when the goal is controlled failover and data integrity. Databases are typically stateful systems, and simply distributing connections does not address replication, quorum, shared storage considerations, or failover coordination. This option is plausible because it seems simpler, but it weakens the resilience of the database tier.