The market for content delivery networks (CDNs) has grown outward in the last decade to encompass more flexible – and cheaper – offerings. That means many sites that couldn't afford a CDN a few years ago are now dipping their toes in. But with a democratized market also come mistakes. Without the professional services provided by higher-end CDN offerings, it's easy to make seemingly small mistakes in setting cache-control headers that result in higher costs and sub-optimal performance. These are easy to fix, but you have to know what to look for.