Azure VM - SQL Always On listener

Hi,

We have x2 Azure VMs for SQL 2014 with a Listener.

However, this Listener IP is not response to ping from another other server, which including the File Share Witness server. It is only ping-able from the x2 SQL servers.

Checked the NSG rule in Azure portal. There is no rule set on any of the subnet.

Is it by design that the Listener IP for AlwaysOn only response to ping from SQL servers? or there is a mis-configuration somewhere?

The Listener is ONLINE and working. 

Thanks