Caching errors with Edgecast CDN


An online retail company is using Edgecast's CDN‎ and somehow certain CSS files are continually being 'half loaded' into cache, ie. It loads half the file into cache and then stops (as if it is interrupted) at a point. So the cache then serves this incomplete file as the new legitimate cache and users see a 'misshaped' front end. This problem remains until the support team manually clear the cache and it loads the full CSS file correctly.‎ 

The CDN support team point to the app devs, and vice versa.‎

Could anyone suggest any troubleshooting, or how to track down whether it is the App or the CDN causing such an error?

Thank you‎
Roger AdamsAsked:
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Shalom CarmelCTOCommented:
Are they using their own origin, or the Edgecast storage?
Roger AdamsAuthor Commented:
I believe they are using their own origin, hosted on dedicated chunky hardware.
Shalom CarmelCTOCommented:
In my (extensive) experience the problem is usually on the origin side.

Are the loading the assets to cache as a workaround? On the purge/load tab, there is an option to pre-warm the cache with a valid object, there is also a simple API,
If they have the rules engine, try to debug the cache state using the "Debug Cache Response Headers" feature.
Roger AdamsAuthor Commented:
thanks for the suggestions. I will have a look at those.

in your experience, are there any 'typical problems' on the client side that could be causing this? Locked files, script jobs, loading timeouts, etc.?

thanks again
Shalom CarmelCTOCommented:
any or all..
A partial list of "funny" issues causing problems:
* An AV agent on IIS server was causing timeouts during scans.
* Load balancer with stickiness based on geo IP distribution was sending all request to a single server in a cluster of 4.
* gzipping on origin

 A web server is usually robust enough to deal with traffic, but the eco system (OS, network) is too often not set up well.

To continue our research:
* Are there any rules in the rules engine touching these objects?
* What is the cache hit ratio (CHR)? Find it in the analytics section.
* What is the distribution of  the cache statuses? Find it in the analytics section too

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