Problem Overview: When attempting to connect to Azure SQL databases through Private Link using SSMS from an on-premises network, users may encounter DNS resolution issues. The Azure SQL Private Link setup requires the addition of a conditional forwarder for the "privatelink.database.windows.net" domain. However, connecting directly to the IP address or using the Private Link FQDN (<server>.privatelink.database.windows.net) will intentionally fail.(https://learn.microsoft.com/en-us/azure/azure-sql/database/private-endpoint-overview?view=azuresql-db#check-connectivity-using-sql-server-management-studio-ssms) To establish a successful SSMS connection, the correct FQDN format (<server>.database.windows.net) must be used.
Solution: To resolve the Azure SQL Private Link DNS resolution issue for SSMS connectivity, please follow the step-by-step instructions below, which include the use of Azure DNS Private Resolver:
Identify the Issue:
- Experience DNS resolution problems when using SSMS to connect to Azure SQL databases through Private Link from an on-premises network.
- Understand the Root Cause:
- Azure SQL Private Link requires the addition of a conditional forwarder for the "privatelink.database.windows.net" domain.
- Direct login attempts using the Private Link FQDN or IP address intentionally fail, as the correct FQDN (<server>.database.windows.net) must be specified for SSMS connections.
Configure Azure DNS Private Resolver:
- In the Azure portal, navigate to your Virtual Network (VNet) settings.
- Enable the Azure DNS Private Resolver feature for your VNet, allowing it to resolve DNS queries for resources within Azure.
Add Conditional Forwarders:
- Open the DNS management console on the DNS server used in the on-premises network.
- Add a conditional forwarder for the domain "privatelink.database.windows.net," pointing to the DNS server responsible for resolving Azure services.
Configure SSMS Connection:
- Open SSMS on the client machine within the on-premises network.
- In the "Connect to Server" dialog, enter the Fully Qualified Domain Name (FQDN) of the server (<server>.database.windows.net) instead of the Private Link FQDN or IP address.
- Provide appropriate authentication details (username and password).
Test SSMS Connectivity:
- Click the "Connect" button in SSMS to establish a connection to the Azure SQL database through Private Link.
- Verify successful login and ensure that you can perform desired operations within SSMS.
Conclusion: By following the above steps, you can resolve the Azure SQL Private Link DNS resolution issue specifically related to SSMS connectivity from your on-premises network. By enabling Azure DNS Private Resolver and adding the conditional forwarder for the "privatelink.database.windows.net" domain as well as <server>.database.windows.net (both), you can ensure that DNS queries from your on-premises network are resolved correctly to Azure resources. Using the correct FQDN format in SSMS connection settings will enable a successful connection to Azure SQL databases. Remember to keep your DNS configurations up to date to ensure proper connectivity and security for your Azure infrastructure.