The available sets are an organization component (resource) of the Azure platform and they manage the operation of two or more instances of a VM. The available sets ensure that the VM instances are always running on different fault and update domains of the Azure platform, so that at least one instance is always online.
Fault Domain: Fault domain in Azure means that all servers in these domains run in the same fire sections, with the same air condition or electrical source which means all physical servers within in those domains, can have an outage at the same time.
Update domain: Update domain in Azure means that all physical servers in an update domain will get updates like firmware, drivers, and OS updates at the same time.
Update domain: Update domain in Azure means that all physical servers in an update domain will get updates like firmware, drivers, and OS updates at the same time.
Let's look at the next novelty in this view: if you look closely, you can see here an instance of the Azure Load Balancer which serves as an entry point to the architecture. The load balancer has the task to forward incoming internet requests to the provided VMs.
The load balancer requires the following additional resources to perform its tasks:
- Public IP address: A public IP address is needed for the load balancer to receive internet traffic
- Frontend configuration: Associates the public IP address with the load balancer
- Backend address pool: It contains the NICs for the VMs that will receive the incoming traffic
Not shown in the diagram are the following resources:
- Load balancer rules: Load balancer rules are used to distribute network traffic among all the VMs in the backend address pool.
- Network address translation (NAT) rules: NAT rules are used to route traffic to a specific VM. But beware, if you want to enable, for example, the RDP for the VMs, you must create a separate NAT rule for each VM.