The requirements for a web application state that it must be architected for high availability. The web application consists of front-end web server and back-end database server components…

A single front-end web server is a single point of failure at the web tier, making this architecture not fully highly available despite the clustered back-end.

Two front-end and two back-end servers without explicit load balancing or clustering do not guarantee automatic failover and traffic redistribution on failure.

A single back-end database server is a single point of failure for the entire application's data layer, negating high availability regardless of the redundant front-end.

Load balancing across two front-end web servers ensures that if one web server fails, the other continues serving traffic without interruption. Clustering the two back-end database servers provides automatic failover for the stateful data tier, which is the most critical single point of failure. Together these two configurations provide full HA coverage at minimum cost because no additional servers beyond the minimum two-per-tier are added.