A.The common root of CIST is the switch with the smallest bridge ID among all switches in the network

B.CIST is a tree calculated by all switches in the network, and its root is the total root in the network

C.The domain root of CIST refers to the switch with the highest priority in a certain domain

D.The regional root of CIST is the root bridge of IST in a certain region

A.Failure time does not exceed 1 minute per year

B.Failure time per year does not exceed 6 minutes

C.Failure time per year does not exceed 9 minutes

D.Failure time per year does not exceed 3 minutes

A.Verification is not enabled on the NTP client, and verification is enabled on the server

B.Both NTP client and server enable authentication

C.Verification is enabled on the NTP client but not on the server

D.Both NTP client and server are not enabled for authentication

A.If multiple backup root bridges are set, when the root bridge fails, the backup root bridge with the smallest MAC address will become the root of the specified MST instance

B.Use the rootsecondary command to specify the backup root bridge in an instance. When the root bridge fails or is shut down, the backup root bridge can replace the root bridge and become the root bridge of the specified spanning tree instance

C.The rootprimary command can be used to specify the first preference in an instance. After the command is specified, the priority of the root bridge cannot be modified

D.If not specified, the root bridge of all instances in the MST region is the root bridge of IST by default

A.Compared with RPT, SPT makes multicast packets reach the receiver through the optimal path, which improves the efficiency of packet forwarding

B.When multicast traffic is forwarded along the RPT, devices along the way have established (S, G) entries corresponding to the multicast source

C.During the process of switching from RPT to SPT, the RP may receive two copies of multicast traffic arriving in the two directions of RPT and SPT. At this time, the RP will send a prune message upstream

D.When the device switches from RPT to SPT, it sends a join message to the multicast source