What is defined as non-cacheable content?

[bdowney]

What is defined as non-cacheable content? For example CGI. Where can I find a complete list of non-cacheable content?

[thomas.chen]

Take a look at this: http://www.mnot.net/cache_docs/ and you can use this tool (http://www.ircache.net/cgi-bin/cacheability.py) to determine if a page is cacheable.

[perherna]

I'm not sure from which side your question was more intended; the actual HTTP code or what makes something cacheable for a caching device like a Cisco Cache Engine so I'll try to answer this from both perspectives.

There is a way to flag a HTTP document as 'non-cachable' in the HTML code. When a caching device sees this it will not write that to object to its cache. This makes frequently updated sites like news or weather sites work with caching devices.

As for non-cacheable port 80 content, I know the Cisco Cache Engine can be tweaked to cache just about anything aside of objects that are set as 'non cahceable' in the HTML code including CGI scripts (caching of CGI objects is disabled by default).

Also from the caching device's perspective there are several methods of flagging traffic to specify what is cacheable and non-cacheable. You can create bypass lists by source or destination IP address, layer 5 regular expression matches, ect.

I hope that helps answer your question.

Cheers,

Perry.