What is diagnostic ports in EX/QFX devices?

-These diagnostic ports are available only on the bigger systems (M,MX,T series) and these ports are located on the control boards of the systems.
-Password authentication for the diagnostics port is used to secure console to a control board or forwarding component on the router.

- On EX/QFX platform, there is no diagnostics port that user can apply password as above.

- Set system [diag-port-authentication] option is hidden configuration on EX

- User will get warning message that the configuration is unsupported on EX platform even it's configurable via hidden command.

The Junos OS accepts and commits this command (set system diag-port-authentication plain-text-password) on unsupported platforms, even though they don’t do anything.