The 5-hour CDN

The text discusses the concept of building a Content Delivery Network (CDN) using web applications and NGINX, a popular open-source web server. It explains that a CDN functions as a distributed caching proxy, hoovering up files from a central repository and storing copies close to users. The author suggests using existing work done by others rather than building from scratch, and provides examples of tools like Varnish, Apache Traffic Server, and NGINX. The text also covers traffic direction methods such as Anycast and DNS load balancing, and emphasizes the importance of redundancy in case a server fails. It mentions monitoring options for detecting issues with servers or the Internet, including Datadog, updown.io, and Honeycomb. The author then discusses caching strategies like cache sharding and onion layers to increase cache ratios and improve performance. The text concludes by highlighting the advantages of using CDNs for improving cache ratios and avoiding bad Internet connections. It also touches upon advanced features that can be added to a CDN, such as image optimization, WAF, API rate limiting, and bot detection.