Web Caching and Replication

5.5. The cache-control Header

The cache-control header can contain multiple directives that control the use of all the caches (if any) that are situated between the client that originally issued the request and the origin server. Thus, the value of the cache-control header is a list of directives, and each directive consists of the keyword identifying the directive and, optionally, the directive value. For example, the following is a valid cache-control header containing three directives.

cache-control:max-age=120,no-transform,proxy-revalidation

The cache-control header may be present in both requests and responses and is thus considered a general header. However, most directives in this header are specific to or interpreted differently in ...