About VS : Vlan and tunnel configuration

Hi Michaelyang , 
the difference is "security and managerial" concerns. 
you’re securing your virtual servers from being accessed by all vlans , so its up to you and based on your needs. 
if you let it as default , you allow all vlans to access your virtual servers , if you specify vlans , you allow only the selected vlans to access your virtual servers. 
> but it is best practice to specify your vlans for security and manage your network traffic well. 
Regars.