Replica DCs on Azure – Switch DNS servers for the VNet

June 17, 2016 at 7:18 am in Azure, Cloud, DC, DNS, hybrid cloud, IaaS, Replica DC, W2K12R2 by Wim Matthyssen

This blog post is part of the step-by-step to deploy replica domain controllers (DCs) on Microsoft Azure which can be found here: http://scug.be/wim/2015/09/28/deploying-replica-dcs-in-windows-azure/

After we successfully installed both IaaS virtual machines (VMs) as DCs there are still some Azure related actions we can perform. One of them is changing the DNS servers used in the VNet (AZU-VNET-01) to primary use the DNS installed on both IaaS DCs. By doing this we will minimize the data (DNS related actions) out of the Azure data center, which will reduce Azure network costs. We can do this changes through use of the Azure Classic Portal or via the network configuration file (NetworkConfig.xml). I will show both steps below, so let’s get started.

By making use of the Azure Classic Portal

1) Logon to the Azure Classic Portal as a Service administrator or Co-administrator

2) In the navigation pane, click Networks and then click the name of your VNet (AZU-VNET-1)

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3) Click Configure

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4) In the dns servers section, delete the on premise DC (GR-DC-01) by clicking the X next to the IP ADDRESS

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5) To add and register both Azure IaaS DNS servers (AZGR-DC-01 and AZGR-DC-02) with the VNet and Azure, just type their name and IP Address in the boxes. I will also add the on premise DNS server (GR-DC-01) as third failback DNS server. When added click Save

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6) When asked click YES, this will start updating the VNet

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7) When finished successfully, click OK

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8) When the DNS list is updated, we must restart all IaaS VMs (AZGR-DC-01 and AZGR-DC-02) connected to the VNet, so they can pick up the new DNS settings

Before the reboot:

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After the reboot:

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9) To check if DNS is working like it should after the changes, ping the on premise DC (GR-DC-01). If all is OK, you should get replies like shown it the below screenshot

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By making use of the network configuration file

1) Logon to the Azure Classic Portal as a Service administrator or Co-administrator

2) In the navigation pane, click Networks, click the name of your VNet (AZU-VNET-1) to select it and at the bottom of the screen click EXPORT

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3) Select your SUBSCRIPTION and click het check mark button

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4) The NetworkConfig.xml file will be downloaded. When finished click View downloads

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5) Click Open folder

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6) Right click the NetworkConfig.xml file and select Edit

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7) You can see in the original file there is just one DNS servers used (GR-DC-01 – 192.168.2.4)

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8) Change the DNS servers like in the screenshot below and save the file

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9) Go back to the Azure portal, click NEW at the bottom, click NETWORK SERVICES, click VIRTUAL NETWORK and then click IMPORT CONFIGURATION

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10) Browse the changed NetworkConfig.xml file and click the arrow

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11) Verify the changes and press the check mark button at the bottom if all is fine

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12) The import will start

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13) When the import is successfully finish press the OK button

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14) Like you can see, the DNS servers (AZGR-DC-01 and AZGR-DC-02) are added

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15) Reboot all IaaS VMs connected to the VNet to adjust their DNS settings

That ends this part of the series. I hope it’s useful, till next time!

Wim Matthyssen (@wmatthyssen)

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