If you are configuring Distributed DDNS Service Nodes in an environment with load balancers, you must ensure that the load balancers have been configured correctly to ensure that updates are not split up.
For example, if you are using GSS-TSIG, two updates are sent: the first update retrieves the TKEY and the second update passes the update with the TKEY. If your load balancer is incorrectly configured, the first update might be sent to one service node and the second update might be sent to a different service node, resulting in a failure.
If you are using Azure load balancers, an admin user would need to configure the load balancer to use Source IP affinity. By configuring Source IP affinity, the connections that are started from the same client device go to the same datacenter endpoint. For more information, refer to https://docs.microsoft.com/en-us/azure/load-balancer/distribution-mode-concepts.