Assuming hello PDU authentication has been disabled, which command re-enables the feature on a FabricPath interface?
A. switch (config-if) # fabricpath isis authentication-type cleartext
B. switch (config-if) # fabricpath isis authentication check
C. switch (config-if) # fabricpath isis authentication-type md5
D. switch (config-if) # fabricpath isis hello-interval
the answer is C
No, answer is B. “fabricpath isis authentication check” indeed:
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5500/sw/fabricpath/6x/fp_n5500_config/fp_n5500_authenticate.html:
Example :
switch(config-if)# fabricpath isis authentication-check
(Optional) Enables an authentication check on the incoming FabricPath Layer 2 IS-IS PDUs for the interface. The authentication check is On by default. (To turn off the authentication check, enter the no form of this command.)