Exam JN0-351 topic 1 question 55 discussion

C is 100% correct. But between A and D, I think A is correct because you need to provide interface also. Here B is not correct because em1 is not correct mgmt interface, it should be em0 interface instead.

C,D are correct

Enable a dedicated management virtual routing and forwarding (VRF) instance. The name of the dedicated management instance is reserved and hardcoded as mgmt_junos; you cannot configure any other routing instance by the name mgmt_junos. The management Ethernet interface (usually named fxp0 or em0) provides the out-of-band management network for the router. There is no clear separation between either out-of-band management traffic and in-band protocol control traffic, or user traffic at the routing-instance or routing table level. The management-instance configuration statement confines the management interface in the dedicated management instance mgmt_junos, and it enables an administrative routing table dedicated to management tasks for the network device.