As a content provider, you may have concerns regarding how caches deal with your site content. In particular, many people worry about dynamic responses, advertisements, and accurate access count statistics. While each of these usually result in uncachable content, some methods are worse than others. In this section, I talk about some of the tradeoffs and what you can do to minimize the wait times for users.
Dynamic responses are generally cache-unfriendly. This doesn’t mean that dynamic content is bad. It does mean that caches cannot help to improve users’ wait times for dynamic pages.
As a webmaster, this is a tradeoff you must carefully consider. How important is the dynamic aspect of your content? Is it worth making people wait for it? Is it worth losing some viewers/customers because the wait is too long? You might say that your customers won’t have to wait because you can build a really big server with really fast hardware. However, your big, fast server does nothing to alleviate wide-area network congestion. Neither can it reduce network round-trip delays, nor make someone’s dial-up connection faster. You’ll have to decide on a balance between dynamic content and cachability.
Advertisements, ad images in particular, are not necessarily at odds with web caching. It really depends on how the system is set up. A number of reasonable approaches are possible. For the following discussion, ...