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This article explains the recommended process for updating a DNS Relay when the virtual machine (VM) it runs on requires an OS upgrade (for example, moving from Ubuntu 18.04 to Ubuntu 22.04).

Relay software itself updates automatically when deployed from the DNSFilter dashboard. However, upgrading the underlying VM image requires redeploying the Relay on a new image.

The steps below use Ubuntu as the example, but the same process applies to other operating systems. To complete the update, redeploy the DNS Relay using the latest configuration and install instructions in the Relay Install section of the DNSFilter dashboard.

Recommended Upgrade Process

Follow these steps to ensure a smooth transition with minimal network disruption.

1. Review and record the IP configuration of each existing relay

2. Generate replacement images

   1. Create new relay images with distinct hostnames for clarity
   2. Assign new IPv4 addresses to avoid conflicts with existing relays

3. Deploy and test the new relays

   1. Set static IP addresses on new relays

   2. Confirm network connectivity using the DNS Relay Deployment Guide

4. Configure networks to route traffic through the new relays

5. Ensure all devices and networks are functioning correctly with the updated relays

   1. Running new and old relays concurrently allows testing before full migration

6. Decommission old relays

   1. Remove old relays from the network 

   2. Devices with static DNS entries must be updated before decommissioning old relays

Alternative Approach: Existing relay IPs can be reused, but migration must occur one relay at a time to prevent network conflicts. The method above provides greater flexibility and minimizes potential downtime.