When I checked BOL for the answer (yes I know I should have the answer in my head) it describes five protocols and calls them Net-Library protocols. They are

Shared Memory

Named Pipes

TCP/IP

VIA

DAC

The last one almost made me click on 5 as the answer. But closer reading showed that DAC is for sysadmin role members only.

The question could have been better worded to say how many Net-Library protocols are available to use. The answer would then be five.

Tim Brimelow