If you are using Akamai service, most of the time you will need to check the cached object validity or the traffic behavior. For Akamai service, adding in some specific Pragma headers will give you the useful information you need during troubleshooting.
Akamai has the useful extension/add-on in Firefox and IE that can append Akamai specific Pragma headers automatically, and in response you will be able to see those useful Akamai information for debugging purpose. If you are Akamai user, you can download EdgeSuite Booster in EdgeControl portal -> Site Accelerator -> Tools -> Development Tools.
Once EdgeSuite Booster gets installed, the process is automated. Open an Akamai site in Firefox will return you the useful information in Firebug console. Take notice on the request Pragma headers, and the response headers start with “X-” below.
Accept text/css,*/*;q=0.1 Accept-Encoding gzip, deflate Accept-Language en-us,en;q=0.5 Cache-Control no-cache Connection keep-alive Host www.website.com Pragma akamai-x-cache-on, akamai-x-cache-remote-on, akamai-x-check-cacheable, akamai-x-get-cache-key, akamai-x-get-extracted-values, akamai-x-get-nonces, akamai-x-get-ssl-client-session-id, akamai-x-get-true-cache-key, akamai-x-serial-no User-Agent Mozilla/5.0 (Windows NT 6.1; rv:11.0) Gecko/20100101 Firefox/11.0
Cache-Control private, max-age=1103 Connection keep-alive Content-Encoding gzip Content-Length 9120 Content-Type text/css Date Sun, 18 Mar 2012 10:59:33 GMT Etag W/"34608-1330928498000" Last-Modified Mon, 05 Mar 2012 06:21:38 GMT Server Apache-Coyote/1.1 Vary Accept-Encoding X-Akamai-Session-Info name=PARENT_SETTING; value=TD X-Cache TCP_MEM_HIT from a118-214-191-15 (AkamaiGHost/22.214.171.124-9183648) X-Cache-Key /L/1745/15811/3h/www.website.com/common/css/style.css X-Check-Cacheable YES X-Serial 1745 X-True-Cache-Key /L/www.website.com/common/css/style.css ntCoent-Length 34608
Explanation on some of the Akamai debug headers.
X-Cache : Cache State
X-Cache TCP_MEM_HIT from a118-214-191-15 (AkamaiGHost/126.96.36.199-9183648)
a118-214-191-15 : Akamai IP Identifier (The Akamai server that serves this request) TCP_HIT : The object was fresh in cache and object from disk cache. TCP_MISS : The object was not in cache, server fetched object from origin. TCP_REFRESH_HIT : The object was stale in cache and we successfully refreshed with the origin on an If-modified-Since request. TCP_REFRESH_MISS : Object was stale in cache and refresh obtained a new object from origin in response to our IF-Modified-Since request. TCP_REFRESH_FAIL_HIT : Object was stale in cache and we failed on refresh (couldn't reach origin) so we served the stale object. TCP_IMS_HIT : IF-Modified-Since request from client and object was fresh in cache and served. TCP_NEGATIVE_HIT : Object previously returned a "not found" (or any other negatively cacheable response) and that cached response was a hit for this new request. TCP_MEM_HIT : Object was on disk and in the memory cache. Server served it without hitting the disk. TCP_DENIED : Denied access to the client for whatever reason. TCP_COOKIE_DENY : Denied access on cookie authentication (if centralized or decentralized authorization feature is being used in config).
X-Cache-Key : Internal Cache Key
15811 : Akamai CP Code 3h : Cache TTL www.website.com : Origin Server Name
X-Check-Cacheable : Cacheability
This determines if the request object is cache-able as set in your Akamai configuration.
Other Tools to get Akamai Debug Headers
If you do not have the access to EdgeControl portal to download the EdgeSuite Booster. You can use “curl” or Fiddler2 to do the same job for you.
curl -I -H "Pragma: akamai-x-cache-on, akamai-x-cache-remote-on, akamai-x-check-cacheable, akamai-x-get-cache-key, akamai-x-get-extracted-values, akamai-x-get-nonces, akamai-x-get-ssl-client-session-id, akamai-x-get-true-cache-key, akamai-x-serial-no" http://www.website.com/style.css
Open Fiddler2, follow below steps.
You will be able to see the Akamai debug headers in Fiddler2 inspector.