Caching errors with Edgecast CDN

Hi,

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?
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Roger AdamsAuthor Commented:
I believe they are using their own origin, hosted on dedicated chunky hardware.
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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.
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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
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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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