Azure Traffic Manager - Incorrect interval for health probe even I configured correctly

Question

Dear Microsoft team.

I am configuring the probing interval for my traffic manager profile to send requests to my custom endpoint (Application deployed in App Service), although 30s second per between two requests but my application continuous received the request in a short time (not event 30s per request).

My Traffic Manager setup:

My App Service (which received the request from Traffic Manager)'s Application Insight request logs:

-> As an image show above you can see the interval between each request are very close together although my setting probe interval at Traffic Manager is 30s.

Note that my App Service is enabled with zone redundancy with 3 instances alive.

I am looking forward to getting your support soon, thank you so much.

Tri Dang.

Answer 1

@Dang Phuoc Tri (FSG.MBI)

Thank you for your patience here.

I did a lab and observed the same health probe behavior as you have observed above and it is an expected behavior of Azure Traffic Manager Health probe monitoring.

Since the App Service is enabled with zone redundancy which has 3 instances alive. Azure Traffic Manager will probe the all the three instances of the App Service.

I was able to validate the observation above by collecting a packet trace at my Web App the packet trace will generate three files for each instance and you can validate the health probe packet as user agent will be Azure Traffic Manager Endpoint Monitor (Reference Image below)

Another aspect of this is that Traffic manager deploys multiple probes from multiple locations for each endpoint. Multiple probes increase resiliency for endpoint monitoring. Traffic manager aggregates the average health of the probes rather than rely on a singular probe instance. The redundancy of the probing system is by design.

This is currently documented here

Hope this helps! Please let me know if you have any questions. Thank you!

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