Tutorial: Create DNS records in a custom domain for a web app

• 3/11/2019
• 5 minutes to read
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You can configure Azure DNS to host a custom domain for your web apps. For example, you can create an Azure web app and have your users access it using either www.contoso.com or contoso.com as a fully qualified domain name (FQDN).

To do this, you have to create three records:

• A root "A" record pointing to contoso.com
• A root "TXT" record for verification
• A "CNAME" record for the www name that points to the A record

Keep in mind that if you create an A record for a web app in Azure, the A record must be manually updated if the underlying IP address for the web app changes.

In this tutorial, you learn how to:

If you don’t have an Azure subscription, create a free account before you begin.

Use Azure Cloud Shell

Azure hosts Azure Cloud Shell, an interactive shell environment that you can use through your browser. You can use either Bash or PowerShell with Cloud Shell to work with Azure services. You can use the Cloud Shell preinstalled commands to run the code in this article without having to install anything on your local environment.

To start Azure Cloud Shell:

Option	Example/Link
Select Try It in the upper-right corner of a code block. Selecting Try It doesn't automatically copy the code to Cloud Shell.
Go to https://shell.azure.com, or select the Launch Cloud Shell button to open Cloud Shell in your browser.
Select the Cloud Shell button on the top-right menu bar in the Azure portal.

To run the code in this article in Azure Cloud Shell:

1. Start Cloud Shell.

2. Select the Copy button on a code block to copy the code.

3. Paste the code into the Cloud Shell session by selecting Ctrl+Shift+V on Windows and Linux or by selecting Cmd+Shift+V on macOS.

4. Select Enter to run the code.

Prerequisites

• You must have a domain name available to test with that you can host in Azure DNS . You must have full control of this domain. Full control includes the ability to set the name server (NS) records for the domain.

• Create an App Service app, or use an app that you created for another tutorial.

• Create a DNS zone in Azure DNS, and delegate the zone in your registrar to Azure DNS.

  1. To create a DNS zone, follow the steps in Create a DNS zone.
  2. To delegate your zone to Azure DNS, follow the steps in DNS domain delegation.

After creating a zone and delegating it to Azure DNS, you can then create records for your custom domain.

Create an A record and TXT record

An A record is used to map a name to its IP address. In the following example, assign "@" as an A record using your web app IPv4 address. @ typically represents the root domain.

Get the IPv4 address

In the left navigation of the App Services page in the Azure portal, select Custom domains.

In the Custom domains page, copy the app's IPv4 address:

Create the A record

New-AzDnsRecordSet -Name "@" -RecordType "A" -ZoneName "contoso.com" `
 -ResourceGroupName "MyAzureResourceGroup" -Ttl 600 `
 -DnsRecords (New-AzDnsRecordConfig -IPv4Address "<your web app IP address>")

Create the TXT record

App Services uses this record only at configuration time to verify that you own the custom domain. You can delete this TXT record after your custom domain is validated and configured in App Service.

New-AzDnsRecordSet -ZoneName contoso.com -ResourceGroupName MyAzureResourceGroup `
 -Name "@" -RecordType "txt" -Ttl 600 `
 -DnsRecords (New-AzDnsRecordConfig -Value  "contoso.azurewebsites.net")

Create the CNAME record

If your domain is already managed by Azure DNS (see DNS domain delegation, you can use the following example to create a CNAME record for contoso.azurewebsites.net.

Open Azure PowerShell and create a new CNAME record. This example creates a record set type CNAME with a "time to live" of 600 seconds in DNS zone named "contoso.com" with the alias for the web app contoso.azurewebsites.net.

Create the record

New-AzDnsRecordSet -ZoneName contoso.com -ResourceGroupName "MyAzureResourceGroup" `
 -Name "www" -RecordType "CNAME" -Ttl 600 `
 -DnsRecords (New-AzDnsRecordConfig -cname "contoso.azurewebsites.net")

The following example is the response:

    Name              : www
    ZoneName          : contoso.com
    ResourceGroupName : myresourcegroup
    Ttl               : 600
    Etag              : 8baceeb9-4c2c-4608-a22c-229923ee185
    RecordType        : CNAME
    Records           : {contoso.azurewebsites.net}
    Tags              : {}

Test the new records

You can validate the records were created correctly by querying the "www.contoso.com" and "contoso.com" using nslookup, as shown below:

PS C:\> nslookup
Default Server:  Default
Address:  192.168.0.1

> www.contoso.com
Server:  default server
Address:  192.168.0.1

Non-authoritative answer:
Name:    <instance of web app service>.cloudapp.net
Address:  <ip of web app service>
Aliases:  www.contoso.com
contoso.azurewebsites.net
<instance of web app service>.vip.azurewebsites.windows.net

> contoso.com
Server:  default server
Address:  192.168.0.1

Non-authoritative answer:
Name:    contoso.com
Address:  <ip of web app service>

> set type=txt
> contoso.com

Server:  default server
Address:  192.168.0.1

Non-authoritative answer:
contoso.com text =

        "contoso.azurewebsites.net"

Add custom host names

Now you can add the custom host names to your web app:

set-AzWebApp `
 -Name contoso `
 -ResourceGroupName MyAzureResourceGroup `
 -HostNames @("contoso.com","www.contoso.com","contoso.azurewebsites.net")

Test the custom host names

Open a browser and browse to http://www.<your domainname> and http://<you domain name>.

You should see the same page for both URLs. For example:

Clean up resources

When you no longer need the resources created in this tutorial, you can delete the myresourcegroup resource group.

Next steps

Learn how to create Azure DNS private zones.