Hi Anu,
VerneMQ internode traffic is not encrypted by default. You'd have to configure any "vmqs" listener to use an SSL cert, as well as configuring the Erlang distribution protocol to use TLS.
The reason for not encrypting is that a cluster is always on an internal (LAN) network. Clustering over WAN is usually not recommended (I do not know what "two different Azure regions" really mean in that regard, though).
Best,
A.