Slow server hello when setting up SSL handshake azure apim

Question

We have several customers that complain about a slow server response when setting up a SSL handshake.

What we see is this:

Client send SSL HELLO.

Server SSL Hello response takes 10 or more seconds.

We can not figure out what this is causing.

In the wire shark trace we see that the server response takes this long.

Answer 1

Hi Corne Hendrickx,

Thank you for reaching out to Microsoft Q&A

In your APIM Instance > Can you visit > Diagnose & solve problems > Availability & Performance > And see if you can get an insight on why the API response is slow.

Refer: https://learn.microsoft.com/en-us/azure/api-management/diagnose-solve-problems#availability-and-performance

APIM’s SSL Hello timing is primarily influenced by the client’s path to your gateway hostname and the certificate chain it receives. Backend API slowness shows after the handshake, and APIM guidance recommends Inspector traces to confirm where time is spent. https://learn.microsoft.com/en-us/troubleshoot/azure/api-mgmt/availability/performance-hit-api-calls