What is Azure-hosted DNS?

How do you communicate with new services once you provision those services in Azure? It's easy to assign a public IP address and use those statically, but that's not good practice. Things like our servers and databases typically have a domain name attached to them in the enterprise environment. There are good reasons to do that, but explaining those reasons is beyond the scope of this post.

What is important here is that these best practices carry over to the cloud, too. So, that begs the question, after provisioning resources in Azure, how do you communicate with those services? There are a few ways to handle domain name creation and DNS in this case. One of those tactics is to use Azure-hosted DNS. So, what is Azure-hosted DNS? Today, we will discuss that. 

An Overview of Azure-hosted DNS

In this video, CBT Nuggets trainer Knox Hutchinson explains what Azure-hosted DNS is, how it affects your Azure resources, and what pitfalls you may run into when using those DNS entries.

What is Azure-hosted DNS?

A common strategy for any cloud deployment is for organizations to create a virtual private network. This is a good practice. If you aren't familiar with what a virtual private network is regarding Azure, think of those as your personal VLAN in the cloud. That's why these virtual private networks are beneficial. They give businesses a way to segregate their cloud services from other cloud customers. 

There's something special that happens with v-nets in Azure, however. Anytime you provision new services in your virtual private network, Azure automatically assigns that resource an FQDN (fully qualified domain name). That domain name is also hosted by Azure automatically. 

Of course, you can create your own domain names for your Azure resources. You can also host and manage your own DNS services, too. There are reasons to create and manage your cloud DNS for provisioned Azure resources, but that's beyond the scope of this article. 

What are the Domain Names that Azure-hosted DNS Assigns?

If you use Azure-hosted DNS, Azure automatically gives a domain name to newly provisioned services when they are created. It doesn't matter if this is a virtual machine or SQL server. They all get domain names.

So, what do Azure domain names look like? They look like this: 

myResource.VnetGUID.cloudapp.net

Take a moment to pick apart that domain name. There are a couple of pieces to understand. First, all domain names assigned by Azure-hosted DNS end with cloudapp.net. This is the standard behavior for Azure. 

Second, the middle part of the domain name is the GUID of your virtual private network. This is nothing more than a unique identifier for your v-net. 

Third, the beginning of the domain name is the name of your resource. If you named your virtual machine MasterServer1, the front of the domain name associated with that resource would be MasterServer1. 

So, let's put all this together. Let's say the GUID of your v-net is 876867sdfs87234g. That's totally fake and not representative of an actual GUID for an Azure virtual private network, but this is only an example. 

In this case, the FQDN for your virtual machine will be: 

MasterServer1.876867sdfs87234g.cloudapp.net.

How to Choose DNS Servers in Azure

After you provision a new service inside your private Azure network, Azure automatically assigns that resource a domain name. That domain name has to go somewhere, though, and that somewhere is DNS. The question is, can you configure your DNS endpoints for these domain names yourself?

The answer is yes. The more straightforward answer is that Azure will automatically host DNS entries, too. 

By default, after a domain name is assigned to a newly provisioned resource, Azure creates a DNS entry in their DNS servers. The IP address for that DNS server is 168.63.129.16.

There is a gotcha, however. Resources configured in different v-nets can not resolve each other’s domain names. This is a security feature and cannot be changed without additional configuration. 

One more note. By default, DNS is configured at the v-net level. That means DNS entries are automatically configured for any new resource in the v-net with the same settings using the same Azure DNS endpoint. However, you can configure DNS at the virtual NIC level, too. So, if you want a specific VM in your v-net to use DNS somewhere else, you can do that. 

How to Learn More About DNS 

Using Azure-hosted DNS can make your IT life easier, but sometimes you need more. That's when you need to learn how to design a network in Azure. Designing networks in the cloud can be tricky. It's like playing Go. It's easy to know but difficult to master. 

Let’s take a step back for a moment, however. What if you need to learn the ins and outs of DNS before implementing hosted DNS solutions in Azure? How do you make your DNS solutions safe and reliable? Learning how to manage DNS online is easy with CBT Nuggets. We have courses for that, too. 

When you are ready to implement hybrid DNS in Azure and Windows Server, we have courses to teach those skills. Many businesses are finding that they need to implement a hybrid IT environment. Managing DNS between local and cloud IT services is an integral part of managing that hybrid infrastructure.