Akamai - The difference between CCU (purging) and ECCU (refreshing) content
A purge request (content removal) will remove the content from cache.
In order to remove content from cache, you can use the Content control utility (CCU) tool and purge specific URL or CP code. If an entire web site reports on the same CP code, a purge will then remove all the web site content from cache. This may cause a spike of traffic going back to the origin.
For a complete site purge, we recommend invalidating the content instead of removing it. You would achieve the same with the CCU API.
A refresh request (content invalidation), will only invalidate the content and not remove it from cache. The next request for that content will trigger an IMS request to the origin to re-validate the content.
* If the time stamp of the object at the origin is more recent than the one in cache, the origin will reply with a 200 and send the new object.
* If the time stamp at the origin is equal or older than the time stamp in cache, the origin will reply with a 304 (Not-Modifed), which will re-validate the content in cache for the duration of the TTL.
Content can be invalidated the following ways:
* refresh by URL using the CCU
* refresh by CP code using the CCU
* refresh by directory using the Enhanced Content Control Utility (ECCU)
* refresh by file extension using the ECCU
CCU: URL or CP codes can be removed or invalidated. A request takes about 7 minutes to propagate through the network
ECCU: directories or file extensions can be invalidated only. A request takes about 40 minutes to propagate through the network.
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