Analytics cluster of size > 1 will not work on Azure nodes without this fix, assuming the Couchbase "best-practices" instructions were followed when configuring the cluster. The second nodes will not be able to successfully join the cluster.
The issue is caused by resolving the name of each node on the node itself, instead of resolving the names to addresses on the caller side. The best-practices document instructs users to assign the public DNS node name to localhost in the hosts file, causing the callers to erroneously attempt to contact nodes on their own loopback interface.
A workaround is to remove the mapping of the node name to localhost on each node's hosts file. This issue is fixed in 6.0.4, 6.5.1, and Chesire-Cat.