I did the following :

  • Made an Azure load balancer to an availability group of 2 VMs
  • Created an HTTP health probe to monitor the site going to /
  • Verified that the site would respond to

The site doesn't come up.

The firewall is fine. If I switch to a TCP probe on port 80then the site comes up.


Somehow I ended up with a space in the path name shown here. Removing it (or creating a file called EXPLETIVE.HTM in the root of the website) solved the issue.

enter image description here

This was verified in my IIS server logs

2017-04-25 00:08:13 GET /+ - 80 - Load+Balancer+Agent - 404 0 0 0

The plus symbol represents the space.

  • 1
    Those spaces can kill! – CtrlDot Apr 25 '17 at 2:17
  • @CtrlDot I still don't understand why no hostname field for VMS - but I've had enough load balancing for one day! – Simon Apr 25 '17 at 2:21
  • You require hitting a particular host header for your http probes? – CtrlDot Apr 25 '17 at 2:22
  • I'm still trying to figure out exactly how I set everything up but I wanted to be able to disable certain sites from particular nodes for various reasons and if host header was recognized I could just stop that site and it would be removed automatically – Simon Apr 25 '17 at 2:33
  • Azure App Gateway might be a better fit. Azure LB is only a layer 4 device, so you won't be able to do that. – CtrlDot Apr 25 '17 at 2:35

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