Checking Network Load Balancing (NLB) and IIS programatically in C#

Question

I intend to write a small program to check IIS service connectivity and statistics through multiple connections in parallel. The IIS service is behind NLB service (and there 3 different service). So what I did so far is:

1. Create an http handler that returns the name of the current IIS server.
2. Create small HTTP client in WinForms application that sends a request to the NLB. In this client: a series of 100 parallel requests through WebClient object is being sent to the NLB service.

Results: When I send the requests to the NLB, always single IIS server responses. When I try to change the URI to the IIS servers specifically - every server responses on its own request. Now, I think that it means that the NLB doesn't do what it is supposed to do, since it navigates always to the same server (for every run, single server answers - it can change, but not for the run).

Is the check that I mention credible for checking NLB? If not, how can I check it through Winforms application?

Thanks in advance.

Answer 1

That is typical behaviour of NLB. It will try and give you the same host each time. You don't want it to pick a random server each time.

You will have much more useful information from examining the IIS Server logs, performance counters or in built monitoring routines.

Answer 2

There is a Affinity setting in NLB manager.

Change this setting from single to None and check the request is going to different server each time.