A cache is a local copy of a file that exists elsewhere. Caching can take place in the browser, on a dedicated machine on a network, or at an ISP.

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240
votes
42answers
31k views

Recovering a lost website with no backup?

Unfortunately, our hosting provider experienced 100% data loss, so I've lost all content for two hosted blog websites: http://blog.stackoverflow.com http://www.codinghorror.com (Yes, yes, I ...
26
votes
4answers
65k views

How do I set expiration headers for CSS, JS, and Images?

I have recently analysed my website with pagespeed addon on firebug. It suggested me to set expiration on CSS, JS and image files. I am wondering how do i do this?
19
votes
2answers
32k views

Headers to prevent 304/If-modified-since/HEAD requests

What headers should I be sending to outright stop all requests to the server after the content has been cached? We have a very high latency server (Sigh, VMWare) so even sending a HEAD request to the ...
17
votes
4answers
6k views

Why don't browsers have jQuery installed?

I'm using jQuery on several of my websites and although I use a CDN to serve it, it just doesn't make sense for visitor to download jQuery each time. jQuery must be the world's most widely used ...
17
votes
1answer
507 views

How do I prevent Google from serving a cached version of my site?

From what I understand I can tell Google to remove pages from their archive if I add the header: <meta name="ROBOTS" contents="NOARCHIVE" /> But won't this also remove the page from search ...
10
votes
2answers
271 views

Control over the Internet Archive besides just “Disallow /”?

Are there any mechanisms to control what the Internet Archive archives on a site? I know to disallow all pages I could add: User-agent: ia_archiver Disallow: / Can I tell the bot that I want them ...
8
votes
3answers
241 views

Is it worth it to change my entire user images file structure to take advantage of simple browser caching?

On one of my mobile sites, I simply store my user's profile images as '1.jpg' in their user folder, and incrementally go from there for any extra pics they upload. This means that whenever they change ...
8
votes
3answers
529 views

Why don't browsers respect cache headers for initial page request?

I'm scratching my head a bit on this. A Drupal site I run is setting appropriate cache headers that should indicate that the page can be cached for 15 minutes. However, every time I hit the page it ...
8
votes
1answer
144 views

Why is spam added to the Bing cache of my landing page?

Please search on Bing "url:testrails.org" and open the cached page. Bing shows random other pages below the content of my own landing page. This is so weird! This is what I found out so far: I have ...
7
votes
4answers
340 views

Any ideas why Google not caching my site?

The site is www.books-for-children.com, developed in Wordpress CMS. It was launched about two months ago and still has not been cached by Google, which seems highly unusual. Any ideas where I might ...
7
votes
2answers
6k views

Cache external static scripts?

In my never ending quest for a faster website, I thought perhaps I could cache some scripts. I'm using Yslow to rate my site, everything is pretty much A (which is great, our website on Pingdom loads ...
7
votes
6answers
722 views

drupal site speed increase

I'm using a drupal site with a theme from rockettheme. The users are member users. The problem is for unknown reason the site is very slow. Takes around 20 seconds to open the page. I have tried ...
7
votes
2answers
2k views

Chrome causing 404's ending with “/cache/[hex-string]/”?

Since the last weeks we see many 404's on our sites caused by Chrome adding /cache/[hex-string]/ to the current page URL. The hex strings we have seen are: e9c5ecc3f9d7fa1291240700c8da0728 ...
7
votes
1answer
194 views

Cloudflare: Cache static HTML when URL has Query String

Quick CloudFlare 'new user' question for you: BACKGROUND: The HTML pages served up by my origin server never change. All dynamic content is download via JavaScript after the page is loaded in the ...
6
votes
2answers
2k views

Apache: How can I force the browser to reload CSS files?

How to force the user's web browser to reload CSS files with Apache Server? I updated my website's CSS file but some users are still seeing problems that would be resolved if their browsers fetched ...
6
votes
2answers
355 views

New requests for /cache/ URLs

A few weeks ago requests following this type of pattern: http://mysite/cache/7a226e8aa3a4380444a329a7b0dd0f40 http://mysite/otherfolder/cache/7a226e8aa3a4380444a329a7b0dd0f40 started to appear ...
5
votes
3answers
284 views

How can I make a “backup” that can serve static pages if the main site goes down?

We've got one server running our company's website. Unfortunately, it sometimes experiences problems. Is there a way to set up another server to serve the static websites, in case the original server ...
5
votes
2answers
5k views

Clearing cache with CloudFlare?

Is it possible to clear or avoid CloudFlare cache while doing development? I'm developing a site that has caching on several levels - WordPress supercache, the caching done by the browser, and ...
5
votes
1answer
1k views

No mod_expires or mod_headers in apache, how can I cache images/js/css files?

Title says it all, we do not have control over our server environment and although we can request for them to recompile apache for us it will not happen overnight. Is there anything we can do is ...
5
votes
1answer
5k views

HTTP Header Cache Time: s-maxage and max-age

I am setting up a CDN for my website, I found the following sample for adding to the 'httpd.conf' file, this is used to adjust the cache-time for client and CDN: ExpiresActive On ExpiresByType image/...
5
votes
1answer
3k views

Can I expect browsers to cache static content served over SSL encryption?

With all the talk about FireSheep I am thinking of switching my web applications to use full https accross the entire site. However, I am concerned about caching. I use a lot of JavaScript, CSS files, ...
5
votes
1answer
902 views

How do Expires headers and cache manifest rules work together?

I find the W3C's official Offline Web Applications specification to be rather vague about how the cache manifest interacts with headers such as ETag, Expires, or Pragma on cached assets. I know that ...
5
votes
3answers
3k views

expires headers and forcing cache-loading instead of 304?

so here is a little mystery. google analytics javascript somehow always loads from browser cache on F5 (in Firefox). i cannot get the same thing to happen with my own scripts. here are the headers ...
5
votes
2answers
205 views

My old webhost has gone out of business. How can I recover the text of my website?

I found my website in the Wayback Machine a few months ago. My old webhost stopped paying for their servers back in August without any notice. I was going to do a backup the day it happened. Is ...
4
votes
2answers
445 views

Prevent browser from caching text file

I have a web application that runs on an Apache server on the intranet of an organisation. In this web application there is a JavaScript function that loads a specific text file via JavaScript xhttp =...
4
votes
2answers
2k views

Does Google cache stylesheets?

Hey guys, we all know that Google caches the HTML of pages, but does it cache the corresponding CSS as well? I ask because a site I used to have and have since closed down is still in the cache and ...
4
votes
2answers
239 views

How can I cause a browser to download a new copy of a web page when it thinks that its cached copy is still valid?

Sometimes when I make small changes to a website, I notice that certain browsers are very stubborn about downloading the page again. Both F5 and CTRL-R are worthless and the only way to fix it is to ...
4
votes
2answers
313 views

Do browsers recognize the same files served by different subdomains?

I have my website assets stored on Amazon S3 and served by CloudFront, from a separate domain name, to act as a cookie-less domain (so website.com for the website and websitestatic.com for static ...
4
votes
1answer
3k views

How to do a cacheable redirection?

When users enter my website example.com, their "preferred" language is detected and they are redirected (using a 301 Moved Permanently redirection) to example.com/en/ (for English), example.com/it/ (...
4
votes
3answers
756 views

What effect does turning off caching in all browsers have on SEO?

What effect does turning off caching in all browsers have on SEO?
4
votes
1answer
5k views

“404. That’s an error.” when viewing from Google cache

My site is getting 404. That’s an error. message when I click on cached from Google search results. This is the error message from Google: That’s an error. The requested URL /search?q=cache:...
4
votes
5answers
6k views

how should cache control be set in the requests

I know that Cache-Control headers can be set on the pages coming out from the web-server (as part of the response). Does anyone know how Cache-Control header should be set on the request? Should it be ...
4
votes
1answer
1k views

How to fix “Leverage browser caching” error from Page Speed plugin

I'm using the Page Speed Firebug plug-in to check my sites. But I don't know how to fix the "Leverage browser caching" error, since I don't know you specify a cache lifetime to the browser in images ...
4
votes
1answer
85 views

Google Cache: Blank Page (Responsive Design) [closed]

I've been aware of this issue for sometime but sadly not had the downtime to address, but I want to ensure that its actually a problem before wasting my time. The problem that I have is that Google's ...
4
votes
2answers
602 views

Mediawiki much slower in Firefox

I've a couple of Mediawiki (1.19.1 with Vector Skin) sites on Dreamhost shared hosting and I've found that access trough Firefox is much slower than trough Chrome. For example at this moment, after ...
3
votes
3answers
3k views

Does CloudFlare cache videos, and would this wildcard Page Rule work for that?

I'm setting everything up in my website to use CloudFlare. This is my example: On videos.domain.com/Folder-A/Folder-B/ there are some HTML files that I would NOT like CloudFlare to cache. But inside ...
3
votes
1answer
884 views

Index of Content on a Defunct Website/Blog

Is there a way to find the content on a defunct website or blog? How do you find the content that was on a website from two or three years back? Google cache doesn't appear to hold information from ...
3
votes
3answers
335 views

Getting google to reindex faster

We run a high-traffic site for a large organization and it was compromised through an editor account. The attacker was able to poison the google cache, and the visible result to us is that if you ...
3
votes
1answer
3k views

How to make CloudFlare cache everything?

I want CloudFlare to cache everything, PHP files too, every request from the domain, I want it to cache it. Is this possible? (There are PHP scripts on the domain that print out images, JS and CSS, ...
3
votes
1answer
168 views

Could AJAX + caching be seen as cloaking?

I have a website where we use a technique to speed up loading times based on a combination of AJAX + caching. Basically, when we have a section in a page with content which is slow to retrieve, we ...
3
votes
1answer
193 views

Image not updating for some users

I don't know if this is the best practice, but we added an image with a snow delay for our school. For some users the image wouldn't come up. Is this a matter of the browser or something else? I had ...
3
votes
2answers
1k views

Find old web content via Google cache or similar

I have a bit of a problem. My client is running a Joomla 1.0 site and some content (text) was lost. There was no backup configured of the MySQL database. The content was lost approx. around the 16:th ...
3
votes
2answers
421 views

What's the minimum age for a Cache-Control header with Akamai?

We're planning an integration with a CDN (likely Akamai) and are trying to determine how low we could go for a max-age value. For a site that could get a few hundred thousand folks hitting the site ...
3
votes
2answers
3k views

How can I make redirections cacheable to speed up load times?

Google PageSpeed says this: Avoid landing page redirects To speed up page load times for visitors of your site, remove as many landing page redirections as possible, and make any required ...
3
votes
1answer
3k views

Google Chrome audit: resources are explicitly non-cacheable?

If I run a Google Chrome audit on a site, it lists all CSS, PNG, JPG, JS files and even the main domain (i.e. www.example.com) under the heading: Leverage browser caching The following resources ...
3
votes
1answer
147 views

Can server break clients' cache settings?

I have disputed a domain name to a cybersquatter that I expect to recover soon. The problem is that the cybersquatter has changed the cache headers and now every user who already visited the site or ...
3
votes
1answer
160 views

Problem with browser caching images

I'm sure many site admins must deal with this sort of problem all the time, but I don't have a really good and simple solution myself. It is what happens when you overwrite an existing image on the ...
3
votes
2answers
2k views

CloudFlare Not Sending If-Modified-Since Headers

I'm trying to reduce my server load by providing 304 Not Modified responses for content where appropriate. CloudFlare is my middle man, so they should be sending If-Modified-Since headers whenever a ...
3
votes
2answers
5k views

URL with query disables caching?

Does having a query string attached to a URL cause browsers to never cache it? For instance, my site does something like this: /radar-picture.png?v=sep2013 And it would appear that FireFox never ...
3
votes
1answer
464 views

Discrepancy between Google cached meta description and description in search result

I have developed a 1 page website to deal with time zone world clocks. I have noticed that Google has the latest version of the page in its cache, so it has access to the latest meta description. ...