For an SRX chassis cluster in transparent mode, which action occurs to signal a high
availability failover to neighboring switches?
A.
the SRX chassis cluster generates Spanning Tree messages
B.
the SRX chassis cluster generates gratuitous ARPs
C.
the SRX chassis cluster flaps the former active interfaces
D.
the SRX chassis cluster uses IP address monitoring
B is correct. Yes, the SRX flaps the former active interfaces, but to let the switches know about it the gratuitous ARP messages are generated. Otherwise the switches would be still sending the messages through previous port.
gratuitous ARPs is not support on chassis cluster transparent mode. so C is the correct answer
gratuitous ARPs is not support on chassis cluster transparent mode
http://www.juniper.net/documentation/en_US/junos12.1×46/topics/concept/security-layer2-transparent-mode-chassis-cluster-understanding.html
on chassis cluster+transparent mode: stp not supported, grati arp not supported, IP address monitoring—Failure of an upstream device cannot be detected. Answer is C.