In the MAC address 00: : :9f:eA. , what represents the Organizationally Unique Identifier (OUI)?（）

A. TTL
B. flags
C. checksum
D. type

A. Layer 2 broadcast frames are processed by all devices on the same VLAN
B. Layer 2 broadcast frames are discarded by routers that connect to multiple VLANs
C. Layer 2 broadcast frames are relayed by routers to all connected VLANs
D. Layer 2 broadcast frames are relayed by switches to devices on the same VLAN

A. Broadcast domains require that the participating devices connect to common switches or hubs.
B. Broadcast domains consist of devices reachable by frames addressed to the Layer 2 broadcast address.
C. Broadcast domains require a gateway device such as a router.
D. Broadcast domains consist of devices that reside on the same VLAN.