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azureload-balancingazure-load-balancer

Why does Azure Load Balancer not work for machines not in an availability set?

I created 2 VMs in the same availability set, and added them to a basic load balancer, and that worked fine.

Then I tried to do the same thing, the only two differences being that the VMs were not in an availability set, and I used a standard load balancer instead of basic.

One difference I noticed is that a standard load balancer will allow you to add VMs to the backend pool even though they are not in an availability set.

However I found that I could not connect to the machines through the load balancer's public IP address. Instead I get a connection timeout error. Why is that?

Solution

  • You are absolutely correct.

    Basic SKU Load Balancer supports Virtual machines in a single availability set or virtual machine scale set as a Backend pool endpoints

    Standard SKU Load Balancer supports Any virtual machines or virtual machine scale sets in a single virtual network as a Backend pool endpoints

    https://learn.microsoft.com/en-us/azure/load-balancer/skus

    To have possibility to connect to Virtual machine via load balancer's public IP you have to configure port forwarding in Load Balancer.

    • Create an NSG rule for the VM, allow connection on RDP 3389 port
    • Create a health probe on Load Balancer
    • Create a load balancer rule
    • Create an inbound NAT port-forwarding rule

    https://learn.microsoft.com/en-us/azure/load-balancer/tutorial-load-balancer-port-forwarding-portal