Load balancers on Availability set

Question

When Load balancers are created on Virtual Machine scale set, do load balancers consider the VMs which are added as part of scale up.

For example, if the load balancers are configured on VM scaleset, now the VMs are added in the scale set, do the load balancers distribute the traffic among the newly added VMs automatically? Or this has to be handled manually?

Also if the new VM is added on Availability set, does the load balancer consider this newly added VM or we have to add this VM in load balancer manually?

Answer 1

For VM scale set - yes, as you associate the scale set resource as the backend pool so this will get updated automatically as you scale out.

https://learn.microsoft.com/en-us/azure/load-balancer/update-load-balancer-with-vm-scale-set#set-up-a-load-balancer-for-scaling-out-virtual-machine-scale-sets

For availability sets, no this is for VM resiliency and as you must associate each individual VM nic with the Azure load balancer it will not automatically add new VM nics to the backend pool so this is manual.