In this lesson, I'll show you the purpose of creating virtual networks and how to plan and implement the subnets that are required to break up your virtual network into individual components. Let's get started. Virtual networks are required in an Azure subscription before you can create resources such as virtual machines. Virtual networks are used to replace the networks that would be in your internal data center and instead allow you to provision a new network up in the cloud based on the same concept of IP addressing. You are able to create multiple virtual networks in your Azure cloud subscription, and that is likely when you have multiple projects or multiple solutions in your cloud that do not need to communicate. By default, virtual networks do not send traffic to other virtual networks in your subscription. This is an advantage because the isolation of virtual networks allow you to protect your resources to ensure that they cannot be accessed by other code components or services running in your subscription. There are scenarios where you would like your virtual networks to be able to communicate, so we'll discuss that in a later tutorial when we talk about routing between your subnets. Virtual networks are based upon the IP addressing scheme. This is similar to the way all computers communicate on network environments. It's gonna be our job to design an IP addressing scheme for our Azure virtual network that is compatible with any other IP addressing schemes that we might be using in other cloud subscriptions or in our local data center. Let's take a look at the interface for building a network in Microsoft Azure. To view or modify the virtual networks that are part of our Azure subscription, we can use the search box or the menu system on the left-hand side of the screen to find the virtual network configuration screens. I'll search for it in the search box up at the top. You can see that the Azure menu item for virtual networks comes up. Let's take a look. You can see that this subscription already has some virtual networks created. It's our goal to actually build a brand-new network, so let's click the Create button at the top left-hand corner of the screen. In the creation screen for virtual networks, the first question that we must answer is what resource group we would like to store this virtual network in. All resources in an Azure subscription must be associated with a resource group, and resources can only be in one resource group. Think of this as a way to organize the resources that might be part of a single solution in your Azure subscription. Let's click the Create new one to create a demo resource group for this demonstration. Now that we've designed the resource group to place our virtual network in, let's give it a name. Let's call it DemoNetwork. Now we'd like to click the Next button to take us to the IP address configuration. You can see here that all virtual networks in an Azure subscription must be given a range of IP addresses that can be assigned to the resources that you will create on this network. An example of a resource that you might create would be a virtual machine, such as a Windows workstation. You can see that the default suggestion by Azure is for us to use the 10.0 address space. Let's change this to be something different. When selecting the IP address ranges for your virtual networks in Microsoft Azure, it's important to make sure that you do not use any IP address ranges that may already be used by your organization. For example, if you have an on-premises data center within your organization and you've already used the IP address space 10.0 in your internal data center, you cannot use the same IP address range in your virtual network. The address range for the virtual network in Azure must be unique for your organization. Let's give it a different address such as 20. Now we must provide a subnet mask. The subnet mask by default is a /16. What this means is that you are going to assign 20.0 as the name of the network, and you're gonna allow the last two sections of the IP address space, 0.0, to be available for unique machine addresses. Let's take a look. Here you can see that Azure has provided an IP address default for this new network. This can be changed, so let's take a look at what Azure is recommending. You can see that the address space on the screen is using 10.0.0/16. This terminology means that the first two parts of this IP address, 10 and 0, will be used for the name of the network. And the 0.0 at the end of the IP address can be changed to identify individual computers on the network. Let's go ahead and accept this default. You can see that the documentation here on the screen says that if we accept the 10.0.0.0/16 configuration of this virtual network, it will allow us to store 65,536 unique IP addresses for computers in this cloud network. That is beyond the theoretical limit, so that is gonna provide more than enough IP addresses for our configuration. It's important when selecting the IP address configuration for a network to ensure that your organization is not using the 10.0 IP address anywhere else in your network infrastructure. What this means is that if you have additional cloud subscriptions, or if you have an on-premises data center, you must make sure that the IP addresses that you use in your Azure virtual network configuration are unique in that they do not overlap any IP addresses that your organization has already used In other places. We're gonna accept the default of 10.0. And you can see, down below, it's asking us to build our first subnet. We do not actually have the ability to create resources such as virtual machines directly on a virtual network. Instead, it's appropriate for us to break up this virtual network into multiple subnets. It's subnets where we will actually create new resources such as virtual machines or SQL databases. So let's go ahead and take a look at the subnet that's recommended by this Azure configuration screen by default. You can see that the first subnet that it wants to create has been given the name default. In addition to that, you can see that they have given that a subnet address range of 10.0.0.0/24. Notice the different number after the slash in this documentation. The /24 now means that the network will include the third number. 10.0.0 will be the name of the first network, and that will allow us to change the last set of numbers for individual machines on this network. This will allow approximately 250 computers to be created on this first subnet called default, and that is usually more than the theoretical limit. Let's go ahead and add a second subnet to see what that would look like. When we click the Add subnet screen, we must give it a name. We'll call it subnet2. Now it wants the subnet address range so that this subnet will know what IP addresses would be valid on this network. This must be unique for your subscription. The existing subnet called default used 10.0.0.0. We cannot use that. So let's use 1.0.0.1. You can see that we have now provided the same subnet mask of /24, meaning that the first three parts of the IP address will be the name of the subnet. And we can see that this is unique. That is a different value than the 10.0.0 that was already allocated. Let's click Add. You can now see in the subnet configuration screen that there will be two subnets created as part of this virtual network. You would perhaps want to create multiple subnets when you want to host resources of different types. For example, on the default subnet, you might host your public web servers that host your company's website, but on subnet2, you might wanna put the databases that those websites use. Therefore, it would allow you additional options to protect the resources on subnet2 and make your databases more privileged or secured to access. Let's click the Create button and find out the results of this creation. When you click the Review and create, Azure will validate that the information that you entered is valid. You can see that our configuration is accurate. So let's click Create and let Azure begin to create these resources for us. The deployment is now in progress. Let's wait a few minutes, and then take a look at the results. You can see when the deployment is complete, we're notified. Let's click on Go to resource. You can see now that we have a brand-new network created called DemoNetwork. This virtual network resides in the resource group called DemoRG. Let's click and see the IP addresses that can be used. We're gonna click on the address space for this virtual network, and we can be reminded that we granted 10.0 as the name of the network for this IP range, and we broke that up into subnets that will fall within that IP address range: 10.0.0, 10.0.1. We are now ready to begin to work with multiple networks to provide routing between virtual networks when you need to. So stay tuned for the next lesson, where I'll show you how to enable routing between multiple virtual networks. Thanks for watching.
