It stores a single response and reuses it with multiple users — so developers should avoid storing personalized contents to be cached in the shared cache. My current understanding is that it is just for intermediate cache server. Even if “no-cache” is in response, intermediate cache server can still save the content to non-volatile storage. The intermediate cache server will decide whether using the saved content for following request. However, if “no-store” is in the response, the intermediate cache sever is not supposed to store the content.
- The no-store request directive allows a client to request that caches refrain from storing the request and corresponding response — even if the origin server’s response could be stored.
- The must-revalidate directive ought to be used by servers if and only if failure to validate a request on the representation could result in incorrect operation, such as a silently unexecuted financial transaction.
- In practice, IE and Firefox have started treating the no-cache directive as if it instructs the browser not to even cache the page.
- Client would ask server if it has new version of data using those headers and if the answer is no it will serve cached data.
- HTTP 1.1 section 13.13 says that “expiration time does not apply to history mechanisms.” The no-cache header describes expiration, and so doesn’t apply to history mechanisms such as the back button.
stale-while-revalidate
HTTP 1.1 section 13.13 says that “expiration time does not apply to history mechanisms.” The no-cache header describes expiration, and so doesn’t apply to history mechanisms such as the back button. Thus, the user can navigate backward to a previous page with no-cache without the server being contacted. In fact, it means “revalidate with server” before using any cached response you may have, on every request. Use a no-cache to make sure that the HTML response itself is not cached. No-cache could cause revalidation, and the client will correctly receive a new version of the HTML response and static assets. The must-understand response directive indicates that a cache should store the response only if it understands the requirements for caching based on status code.
- HTTP allows caches to reuse stale responses when they are disconnected from the origin server.
- For example, you may want to use reload on a service worker and background sync, but use default for the web page itself.
- If no request happened during that period, the cache became stale and the next request will revalidate normally.
- As you identified, no-cache doesn’t mean there is never caching, but rather that the user agent has to always ask the server if it’s OK to use what it cached.
- In the must-revalidate case the client is allowed to send a If-Modified-Since request and serve the response from cache if 304 Not Modified is returned.
If the no-cache directive does not specify a field-name, then a cache MUST NOT use the response to satisfy a subsequent request without successful revalidation with the origin server. This allows an origin server to prevent caching even by caches that have been configured to return stale responses to client requests. HTTP allows caches to reuse stale responses when they are disconnected from the origin server. Must-revalidate is a way to prevent this from happening – either the stored response is revalidated with the origin server or a 504 (Gateway Timeout) response is generated. Cache that exists between the origin server and clients (e.g., Proxy, CDN).
Traffic
And something else I’ve just considered, without Last-Modified or ETags, the browser can only fetch the whole resource again. However with ETags, I’ve observed that Chrome at least seems to revalidate on every request. Which makes both these directives moot or at least poorly named since they can’t properly revalidate unless the request also includes other headers that then cause ‘always revalidate’ anyway. Client would ask server if it has new version of data using those headers and if the answer is no it will serve cached data.
Cache directives
For content that’s generated dynamically, or that’s static but updated often, you want a user to always receive the most up-to-date version. When you update the library or edit the picture, new content should have a new URL, and caches aren’t reused. The React library version will change when you update the library, and hero.png will also change when you edit the picture.
In the fast-paced internet era, delivering up-to-date content to users is crucial. Browser caching, while speeding up website loading, poses challenges in serving recent updates. Fortunately, developers can leverage meta HTML tags to control caching behaviour, ensuring users receive the latest content promptly. This article explores the significance of browser caching and demonstrates the use of meta HTML tags to enhance web speed. To answer the question, there are two players here, the client (request) and the server (response).
Your Answer
Many browsers use this directive for reloading, as explained below. Must-understand should be coupled with no-store for fallback behavior. Note that s-maxage or must-revalidate also unlock that restriction. This feature is well established and works across many devices and browser versions. In April 2024, DuckDuckGo introduced Privacy Pro, a paid subscription that includes a VPN, Personal Information Removal, and Identity Theft Restoration.63 The subscription launched to users of the DuckDuckGo browser in the United States.
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Browsers usually add no-cache to requests when users are force reloading a page. No-cache allows caches to store a response but requires them to revalidate it before reuse. If the sense of “don’t cache” that you want is actually “don’t store”, then no-store is the directive to use. This section lists directives that affect caching — both response directives and request directives. In the must-revalidate case the client is allowed to send a If-Modified-Since request and serve the response from cache if 304 Not Modified is returned. Must-revalidate plus the fact that server responses becomes stale right away.
Alright, this is due to the pain that godaddy gives me by implementing their own caching in a MANAGED WORDPRESS hosting. I looked it up and as it turns out, their flush caching facility is not available to me in the wordpress dashboard as it is a subdirectory /wp/ installation. Find centralized, trusted content and collaborate around the technologies you use most.
No-cache tells it to store the response in the cache, and a later request without it might trigger internal cache. Imagine that clients/caches store a fresh response for a path, with no request flight to the server. The client indicates that an already-cached response should be returned. If a cache has a stored response, even a stale one, it will be returned. If no cached response is available, a 504 Gateway Timeout response will be returned.
In reality, if you’re mixing up no-cache and no-store on the client, very little would change. Then, just a couple of headers get sent and there will different internal responses handled by the browser. An issue can occur if you use no-cache and then forget to use it later.
If copied, the second would overwrite the first and thefourth would overwrite the third because of the http-equivdeclarations AND fail with the W3C validator. At most, one could haveone of each http-equiv declarations; pragma, cache-control andexpires. These are completely outdated when using modern up to date browsers.After IE9 anyway. Chrome and Firefox specifically does not work with these bqqq as you would expect, if at all. You can add a long max-age value and immutable because the content will never change. Note that the major browsers do not support requests with min-fresh.
Disable Browser Caching with Meta HTML Tags
If you forget to add private to a response with personalized content, then that response can be stored in a shared cache and end up being reused for multiple users, which can cause personal information to leak. The must-revalidate response directive indicates that the response can be stored in caches and can be reused while fresh. If the response becomes stale, it must be validated with the origin server before reuse. When a user reloads the browser, the browser will send conditional requests for validating to the origin server.