How to make Windows DNS and WINS settings persist in an Azure VM?

Question

I have a domain controller set up in an Azure VM, and a couple of other servers also set up as VMs. When I set up the server VMs, I configured DNS and WINS to point to the IP address of the DC and joined them to the domain. However, these settings don't survive a shutdown (where the VM is deallocated). When the VM is started back up, DNS and WINS are empty, and domain authentication does not work.

I read that I should provision new VMs via PowerShell commandlets, specifically setting up domain joining. I tried that, and maybe I got something wrong, but it didn't work -- the newly provisioned VM was not joined to the domain, and did not have DNS/WINS set to point to the domain controller.

In any event, my question is: is there any way to re-configure an existing VM to retain network settings through a shutdown or is my only option to figure out how to provision a brand new VM to be married to the domain controller, and then to start from scratch?

Thanks!

Answer 1

You shall never use static configuration on your Azure VM! Neither for IP Addresses, nor for DNS Settings. What I recommend to use is a long story you can read here. It is tested, validated and proven to be effective. A short extract follows:

You should setup at least two sub-nets. Leave one solely for the DNS (and AD/DC if it happens to be the same server). Put all rest of the machines in the other Sub-Net. Thus, you will have 100% predictable IP Address of the DNS Server machine. Having that in mind, configure the DNS for the virtual network via the portal or via PowerShell. But explicitly configure DNS Server for that virtual network. Set IP address for the DNS - the one that you know it will have!

Please do never forget - never manually change network configuration settings for an Azure VM! Doing so is a path to failure.

The above method will help you resolve DNS issue. Now, for the WINS. I don't think you can configure WINS via Virtual Network settings. So, if your VM really loses WINS config, you can create a small powershell script that runs locally on each VM to configure WINS settings upon boot. You can either make this script more generic by looking up the DHCP assigned DNS server and use the same IP Address for WINS, or just put it static, because you know what the IP Address of DNS server will be.

Answer 2

Anton presents a clever and perfectly workable solution, but I wanted to understand what exactly I was doing wrong, because Microsoft guidance suggests that it should be perfectly possible to set up and maintain an Active Directory domain the in the Azure cloud without putting the DC into its own subnet.

After a lot of trial and error (mostly error), I finally figure it out. This is not well documented, so hopefully this will help someone:

In Windows Azure, cloud service is another term for application, or a set of components that scale together. A cloud service is assigned a single DNS name and a single external IP address. In the context of virtual machines, you typically have a 1:1 correspondence between a cloud service and a virtual machine. You only add additional virtual machines to an existing cloud service when you want Azure to automatically load balance and distribute requests among the VMs inside that cloud service, treating them as if they were one.

This brings me to my mistake. Not fully understanding the above, I was attempting to add a new worker virtual machine to the cloud service in which I set up my Domain Controller. That is not a supported configuration. Once I understood that, and properly configured a new VM into its own cloud service, associated with the domain controller as DNS server, everything worked perfectly.