How can high availability be ensured during maintenance?

Ensuring high availability during maintenance is crucial to retaining service continuity and minimizing downtime. Adding a redundant web server behind a load balancer effectively achieves this goal. In this approach, the load balancer distributes incoming traffic across multiple web servers, allowing one server to take over if another goes offline for maintenance. This redundancy means that users can still access the service even when one server is down, maintaining the availability of the application.

This strategy is particularly effective because it allows for planned maintenance or upgrades without disrupting the user experience. As traffic is directed to the operational servers, users remain unaware of the maintenance activities, ensuring that application functionality is preserved.

In contrast, increasing server capacity may improve performance during peak times but does not inherently contribute to redundancy. Optimizing server performance focuses on enhancing efficiency and speed rather than availability during maintenance. Similarly, using a content delivery network (CDN) can help with distributing content but does not provide failover options for backend server maintenance. Therefore, adding a redundant web server behind a load balancer is the most direct method for ensuring high availability during maintenance activities.