Response Times

Sometimes in HAR we see 0 sec Response times for few of the request, what is the reason behind this?

Here is what we believe is happening:

The explanation is that the request are being stopped by a layer before the final web app, a load balancer or a process that validates the request and is returning a small response, very fast, thats why they see 0 sec response times, saying something similar to "The url has moved. Find it in this url: ....", with response code 200. So appvance is hitting this layer and getting a valid response back.

Since we do not know what the expected response is we see this as a valid response and mark that step as passed

Which arguably it is a valid step

But since we never jump to the new url the app server never sees the traffic.