Azure

• Azure Account is composed of
  • subscriptions
  • tenants
• A subscription can be connected to only one tenant, whereas one tenant can be linked with multiple subscriptions
  
• Azure Subscription support plans Refer Here
• Free tier: 12 months (some services) + Always free services + 200 $ (1 month expiry) Refer Here
• Refer Here for knowing limits and quotas of your account

Networking

• In Azure Virtual Networks is a service for creating networks
• Any resources can be connected in a subnet not virtual network directly
• Virtual Network and subnets are scoped to Region/Location in Azure
• Azure Virtual Network can have multiple subnets and every virtual network will have a default routes that enable all the internal communication.
• Default behavior can be changed
  
• When we create a vm in azure the following networking components will be created
  • virtual network with one subnet
  • network interface with private ip
  • network security group
  • public ip address which can access the network interface