AZ-900 Certification Notes

Chapter 5 - Virtual Network

A virtual network (VNet) enables many types of Azure resources, such as Azure virtual machines, or VMs, to securely communicate with each other, the internet, and on-premises networks. A virtual network is virtual because, while you get access to it, you don't have any access to the hardware. Just like a virtual machine, it's yours to use, but the physical hardware is hidden away.

Address Space

An address space is the range of IP addresses that are available. Every service or resource that is connected to a VNet will get its own unique address on that VNet within the address space. That's how services on the same VNet can find each other and communicate.

Subnets

Subnets enable you to segment the virtual network into one or more virtual networks and allocate a portion of the virtual network's address space to each subnet. Doing that, you can have multiple virtual networks on the same VNet.

• Resource Grouping
  • Group resources onto the same subnet to make it easier to keep an overview
• Address Allocation
  • More efficient to allocate addresses to resources on a smaller subnet
• Subnet Security
  • Use network security groups to secure individual subnets

Subnet Regions & Subscriptions

• Regions
  • A VNet belongs to a single region. Every resource on the VNet must be in the same region too
• Subscriptions
  • A VNet belongs to just one subscription, but a subscription can have multiple VNets

Cloud Advantages

• Scaling
  • Adding more VNets or more addresses to one is simple
• High Availability
  • Peering VNets, using a load balancer, or using VPN gateway all increase availability
• Isolation
  • Manage and organize resources with subnets and network security groups

VNet Peering

This feature lets you connect 2 or more virtual networks in Azure. Traffic between virtual machines in a peered network uses the private Microsoft backbone network and never passes through the public internet. Just like if the VMs were on the same virtual network.

Peering Benefits

• Low Latency, High Bandwidth
  • Resources in virtual networks are connected with a low-latency, high-bandwidth connection
• Link Separate Networks
  • Resources in separate virtual networks can communicate with each other
• Data Transfer
  • Transfer data easily between subscriptions and deployment models in separate regions

Exam Tips

A virtual network is a fundamental part of your Azure infrastructure.

• An address space is range of IP addresses you can use for your resources
• A subnet is a smaller network, which is part of your VNet. Use these for security and logical division of resources
• A VNet is in a single region and single subscription
• VNets in the cloud can scale, have high availability and isolation