FAQ

Determining HTTP Response Cacheability

FAQ ID:    FAQ1287
Version:    4.0
Status:    Published
Published date:    03/04/2011
Updated:    03/09/2011
 

Answer

A response cannot be considered cacheable if the request was already deemed uncacheable.  If the request was considered cacheable, the response can still determine that it is uncacheable based on the following:

 

 

 

 

HTTP Response Code

 

Cacheable ?

 

 

cache negative = N

cache negative = Y

force_cache(all)

<=99

N

N

Y

100-199

N

N

Y

200

Y

Y

Y

201-202

N

N

Y

203

Y

Y

Y

204-206

N

N

Y

207-299

N

N

Y

300

N

Y

Y

301

Y

Y

Y

302-303

N

N

Y

304

N

N

N

305

N

Y

Y

306-399

N

N

Y

400

N

N

Y

401

N

N

N

402-406

N

Y

Y

407

N

N

N

408-409

N

Y

Y

410

Y

Y

Y

411-413

N

N

Y

414

N

Y

Y

415

N

N

Y

416-499

N

N

Y

500-505

N

Y

Y

506-599

N

N

Y

600-

N

N

Y

 

Note: The default value of 0 means cache negative  = N. The negative-response caching time can be configured with the following :

a.      Auth
b.      Cache-Control: private, no store, or no cache
c.      Pragma: no-cache
d.      Set-Cookie
e.      Varies
f.      www-auth

 

3. Type N object (object contains no info that would provide any insight into its expiration/refresh) with cookie or parameterized URL that is not overridden by config is not cacheable

 

 

 

5. The object is greater than the maximum cache size allowed

4. The response has no headers or the headers are greater than 8K then it is not cacheable

2. The presence of the following headers:

#(config caching) negative-response <minutes>
Specifies that negative responses should be cached for the specified time. Default is 0 minutes.

1. Response code


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