COMPUTER NETWORKING

Detailed explanation-1: -NSGs can be associated to subnets or individual network interfaces (NIC) attached to VMs. When an NSG is associated to a subnet, the rules apply to all resources connected to the subnet. Traffic can further be restricted by also associating an NSG to a VM or NIC.

Detailed explanation-2: -A network security group (NSG) in Azure is the way to activate a rule or access control list (ACL), which will allow or deny network traffic to your virtual machine instances in a virtual network. NSGs can be associated with subnets or individual virtual machine instances within that subnet.

Detailed explanation-3: –NSGs can be applied at NIC ie network interface card (of VM) or subnet level(not VNET). It must be noted that NSG cannot be applied to the virtual network as a whole.

Detailed explanation-4: -NSG is mainly used for filtering traffic in and out of the Virtual Network (Vnet) in Azure . If you implement NSG at the subnet level all VMs in that subnet will be applied with the rules imposed in NSG.