How can azure select the best location of endpoint?

Question

In the manual of CDN of Azure, end points are propagated in 1minute ~ 90 minutes.
But where are they propagated?
Let's assume that I create a endpoint and it is propagted to Korea(Actually I don't know where it is propagated. Just assume..)
Some of my clients wants to access to my storage. One wants to access from USA, another client wants it from Europe.
In this case, my customers are far from my end point.

If the end point is propagated to USA, end point is closer to my customers.
But how can Azure know which location is best to locate the end point?
Azure doesn't know where my custmers access from.
If end point is propagated to Korea, the customers can't have good experience.
How azure can choose the location? I think the location is fixed after propagated and is not available to move.

Thanks,

Answer 1

Hello @youngmin.yoon ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

Propagation of Azure CDN means the replication of your CDN endpoint configuration via an API to the respective CDN partner (Standard Akamai usually completes within one minute, Standard Microsoft in 10 minutes, and Standard Verizon and Premium Verizon in up to 30 minutes). After creating a CDN endpoint, it will not immediately be available for use, as it takes time for the registration to propagate through the CDN partner. This propagation time has nothing to do with the nearest POP location or any location.

Azure CDN relies on DNS. The DNS routes the end user request to the best performing POP location, which is usually the POP that is geographically closest to the user.

To understand how does Azure CDN find closest location to a client, please refer :
https://learn.microsoft.com/en-us/azure/cdn/cdn-overview#how-it-works

If you want to find out on which Geo POP edge the request landed, you can make use of the AzureCdnAccessLog.
The logs can be viewed under your Log Analytics profile by running a query. A sample query would look like: AzureDiagnostics | where Category == "AzureCdnAccessLog"

The logs will provide various details, out of which you can find the below info as well:
ClientIp : The IP address of the client that made the request. If there was an X-Forwarded-For header in the request, then the Client IP is picked from the same.
POP : Short name of the edge where the request landed.

Once you find the short name of the POP edge, you can check the same in the below article to find the exact location:
https://learn.microsoft.com/en-us/azure/cdn/microsoft-pop-abbreviations

For more information on Azure CDN logs and how to set them up, please refer : https://learn.microsoft.com/en-us/azure/cdn/monitoring-and-access-log

NOTE : The HTTP raw logs feature is available for Azure CDN from Microsoft. The HTTP Raw logs feature is available automatically for any profiles created or updated after 25th February 2020. For CDN profiles created earlier, one should update the CDN endpoint after setting up logging.

Each Azure CDN product has a distinct way of building its CDN infrastructures, hence Microsoft recommends against using POP locations to decide which Azure CDN product to use. Instead, you should consider its features and end-user performance. Test the performance with each Azure CDN product to choose the right product for your users.

Kindly let us know if the above helps or you need further assistance on this issue.

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