Setting Up DNS on Azure

This article provides step-by-step guidance for Setting Up DNS on Azure to support Redis clusters. It includes Prerequisites, a detailed Step-by-Step Setup using Azure DNS Zones, an Alternative Load Balancer Option, and a Troubleshooting section for common DNS issues. This guide ensures your Redis cluster nodes are properly reachable via FQDN for high availability and internal routing.

Prerequisites

• Access to an Azure Subscription with DNS Zone management permissions
• A registered domain (e.g., example.com) and the ability to delegate subdomains
• Public IP addresses of each Redis cluster node
• For production use, you must use Azure Public DNS Zones—Private DNS zones don't support custom NS delegation

Step-by-Step: DNS Setup on Azure

1. Choose a Cluster Subdomain
   • Example: cluster1.example.com
   • This becomes your Redis cluster’s permanent Fully Qualified Domain Name (FQDN).
2. Create DNS Zones in Azure
   • Navigate to DNS Zones in the Azure Portal.
   • If your parent domain (example.com) doesn’t exist yet, create it first.
   • Then create a second DNS zone for your Redis subdomain (cluster1.example.com).
3. Create NS Records in the Parent Zone

   • In the example.com zone, add NS records to delegate the cluster subdomain to Redis nodes:

     cluster1.example.com. NS node1.cluster1.example.com.
     cluster1.example.com. NS node2.cluster1.example.com.
     cluster1.example.com. NS node3.cluster1.example.com.

4. Create A Records in the Cluster Zone

   • In the cluster1.example.com zone, add an A record for each node:

     node1.cluster1.example.com. A [External IP of Node 1]
     node2.cluster1.example.com. A [External IP of Node 2]
     node3.cluster1.example.com. A [External IP of Node 3]

5. Set the FQDN During Cluster Installation
   • Enter cluster1.example.com in the Cluster Name / FQDN field during Redis installation.
   • This value is immutable post-installation.
6. Validate DNS Propagation
   • Use nslookup, dig, or dnschecker.org to confirm DNS resolution is functioning globally.

Alternative: Using a Load Balancer

If DNS setup isn't feasible:

• Use an Azure Load Balancer to distribute traffic to Redis nodes.
• Be aware: This limits certain Redis features like transparent failover and dynamic endpoint generation.

Troubleshooting Common Issues

Additional Resources

Redis Networking with Azure

Redis DNS Configuration Docs

Azure DNS Overview

Set Up Redis Cluster with Load Balancer