What is one of the main roles of a CDN in web applications?

One of the main roles of a Content Delivery Network (CDN) in web applications is to reduce latency for website requests. A CDN achieves this by distributing content across multiple geographically dispersed servers. When a user makes a request for a webpage, the CDN directs that request to the nearest server, which reduces the distance the data has to travel. This leads to faster load times and a more efficient delivery of content, significantly enhancing the user experience. By minimizing latency, CDNs not only improve the speed of content delivery but also help accommodate higher traffic loads without sacrificing performance.

The other choices relate to aspects not directly managed by a CDN. While monitoring server uptime is important for web infrastructure management, it is not a primary function of a CDN. Improving search engine rankings involves SEO strategies, which may not directly involve latency reduction. Storing all website data locally would counter the very purpose of a CDN, which is to distribute data across various locations rather than keep it centralized.