Azure traffic manager weighted routing method - traffic not going to one region

Question

Traffic manager has weighted routing method, two regions are given 50-50 weight, all the requests are going to 1 region, how to check the reason why the request is not sent to the other region?

Answer 1

Hello @Arbina Inamdar ,

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

I understand that you have deployed an Azure Traffic manager with weighted routing method where two regions are given 50-50 weight but all the requests are going to 1 region and you would like to know why the request is not sent to the other region.

While using the weighted routing method, it is important to understand that DNS responses are cached by clients and by the recursive DNS servers that the clients use to resolve DNS names. This caching can have an impact on weighted traffic distributions. When the number of clients and recursive DNS servers is large, traffic distribution works as expected. However, when the number of clients or recursive DNS servers is small, caching can significantly skew the traffic distribution.

These DNS caching effects are common to all DNS-based traffic routing systems, not just Azure Traffic Manager. In some cases, explicitly clearing the DNS cache may provide a workaround. If that doesn't work, an alternative traffic-routing method may be more appropriate.

Refer : https://learn.microsoft.com/en-us/azure/traffic-manager/traffic-manager-routing-methods#weighted-traffic-routing-method

Like I mentioned above, weighted routing feature requires a very large number of queries for the responses to eventually even out.
Even if a huge number of queries were sent, each distinct LDNS (Local DNS) resolver that handles it will send only one query and then cache that answer for your TTL (60 seconds). If you send huge queries over a longer timespan and get past the 60-second TTL, you can separately verify that's true.

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

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Answer 2

@Arbina Inamdar :
You can check Traffic Manager diagnostic logs and monitor the same.

References:
https://learn.microsoft.com/en-us/azure/traffic-manager/traffic-manager-diagnostic-logs
https://learn.microsoft.com/en-us/azure/traffic-manager/traffic-manager-monitoring