User Profile Disk (UPD) is one of the most commonly used technologies for user profiles in RDSH (Remote Desktop Session Host) and VHD (Virtual Hard Disk) environments. Which of the following protocols is used by UPD?

Answer options:

A.SMTP
B.User Datagram protocol (UDP)
C.Telnet
D.Server Message Block (SMB)
E.Gopher

Correct Answer: D 
UPD needs Storage Spaces Direct (S2D) to meet the performance requirements. It is a Server Message Block (SMB) protocol that is used by UPD. Here, the profile is copied to the Virtual Machine in which the target user is being logged.
Option A is incorrect. UPD doesn’t use SMTP protocol.
Option B is incorrect. UPD doesn’t use the UDP protocol. Rather, it uses SMB protocol.
Option C is incorrect. Telnet is not the right protocol to be used by UPD.Option D is correct. It is a Server Message Block (SMB) protocol that is used by UPD.Option E is incorrect. Gopher protocol is not used by UPD.Reference: 
To know more about FSLogix profile containers and Azure files, please visit the below-given link: 

https://docs.microsoft.com/en-us/azure/virtual-desktop/fslogix-containers-azure-files#azure-files-integration-with-azure-active-directory-domain-service