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Azure Virtual Network Primer: Overview and Q&A for IT Pros

By Nirmal Sharma (Send Email)
Posted September 23, 2014

Virtual Networks in Azure enable you to create your own virtual lab in the cloud. You can create a few virtual machines in Azure and then connect these virtual machines using an Azure Virtual Network.

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Azure Virtual Networks not only allow you to set up a virtual lab in the cloud but also enable connectivity to on-premises resources using Site-to-Site and Point-To-Site VPN connections.

You can easily extend your data center by connecting your on-premise network to an Azure virtual network. Windows Server Tutorials Each Azure Virtual Network also acts as a DHCP server, which allows you to configure a DNS server to be leased out when you spin up a virtual machine in the cloud. The Azure Virtual Network is sometimes referred to as VNET for short.

Here's a list of Questions and Answers for Azure Virtual Networks we have compiled for your easy reference.

    1. Q. Can I use VNET for any other services?
      You can only use VNET in Microsoft Azure for connecting virtual machines and Cloud Services. At the time of this writing, other Azure components do not benefit from VNET.
    2. Q. What options are available to create an VNET?
      There are two ways to create an VNET — by using the Azure Management Portal and by using a virtual network configuration file, which is an XML file.
    3. Q. Can I use a Public IP address range in VNET?
      You cannot use a Public IP address range. You can only use IP addresses in the following private IP address ranges: - (10/8 prefix), - (172.16/12 prefix), and - (192.168/16 prefix).
    4. Q. How many virtual networks can I create in Azure?
      There's no limitation. You can create as many as virtual networks you need. It is important to remember thought that you can create virtual subnets only in the Private IP Address range and they must not overlap.
    5. Q. Can I use all the IP addresses of a virtual subnet?
      There are a few addresses of a virtual subnet that are reserved. For example, you cannot use .1 as the last IP address of a virtual subnet. There are also a few IP addresses that are reserved by the Azure Cloud services.
    6. Q. Can I ping the default gateway address of a virtual subnet?
      No, you cannot ping the default gateway address of a virtual subnet.
    7. Q. Does VNET support Layer 2?
      Virtual Networks in Azure only support Layer 3 overlay networking. So you cannot bring your own Layer 2 VLANs in Azure.
    8. Q. Can I create custom routes?
      There isn't a way to create custom routes for a virtual subnet assigned to an VNET.
    9. Q. Can I use multicast or broadcast modes in virtual network?
      Virtual Networks can only work in unicast mode. So, in other words, multicasting and broadcasting functions are not supported by VNET.
    10. Q. What all protocols are supported by VNET?
      Azure virtual networks only support TCP/IP protocols.
    11. Q. Can I add additional subnets to an VNET?
      You can always configure additional subnets in a virtual network.
    12. Q. Can I change the virtual network or subnet of a virtual machine in Azure?
      You cannot do so. You must delete the virtual machine and then assign to an VNET of your choice.
    13. Q. Can I modify VNET configuration?
      You can modify subnet configuration. For example, You can add, remove, expand or shrink a subnet if there are no virtual machines or services deployed within it. You can do this by using PowerShell cmdlets or the NETCFG file. You can also add, remove, expand or shrink any prefixes as long as the subnets that contain the virtual machines or cloud services are not affected by the change.
    14. Q. Can I modify my subnets in Virtual Subnet?
      You can modify subnet configuration as long as there aren't any virtual machines using these subnets. However, you cannot modify a subnet once virtual machines and services are using that subnet.
    15. Q. Can I deploy a Web Server in a VM and have it accessed over the Internet?
      Yes. All services deployed within an VNET can connect to the internet. Every cloud service deployed in Azure has a public IP Address assigned to it. You will need to configure the necessary endpoints to enable these services to accept connections from the internet.
    16. Q. Can I use IPv6 in Azure Virtual Network?
      No. At the moment, only IPv4 is supported by virtual networks.
    17. Q. Can a virtual network span regions?
      No. Virtual Machine networks are created in a single region. You are only allowed to select a single region when creating a virtual network.
    18. Q. Do virtual networks talk to each other?
      VNETs do not talk to each other by default, but if you need to allow communication between different VNETs in Azure, you can use REST API or Powershell commands to do so. There are a few things you need to take into consideration before connecting two virtual networks in Azure, though. For example, you must not use the same IP Address range or virtual subnet in both the virtual networks.
    19. Q. How many DNS Servers can I configure in an VNET?
      You configure a DNS server name in an VNET so when a virtual machine initializes it configures the DNS server in the TCP/IP property. You can configure a maximum of 12 DNS servers in a virtual network.
    20. Q. I changed my DNS server on the virtual network. Will virtual machine receive the new DNS server configuration automatically?
      You must restart the virtual machines if you need them to receive the new DNS server address. Please also note that virtual machines must be restarted in order to receive the new DNS server address and the Ipconfig /renew command does not work.

Nirmal Sharma is a MCSEx3, MCITP and Microsoft MVP in Directory Services. He has specialized in Microsoft Technologies since 1994 and has followed the progression of Microsoft Operating System and software. In his spare time, he likes to help others and share some of his knowledge by writing tips and articles on various sites and contributing to Solution IDs for www.Dynamic-SpotAction.com. Nirmal can be reached at nirmal_sharma@mvps.org.

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