A.BGP attribute can be extended to 256 types

B.Well known discretionary attribute may not be included in each BGP update message, such as origin attribute

C.AS_PATH is an optional transitive attribute

D.Till now, there are 16 BGP attributes

A.The router deletes a group membership only when it receives a Leave message for this group.

B.The router periodically sends Query messages. After a receiver host receives the Query message, the receiver host sends a Report message.

C.The router maintains a timer for each group membership which it refreshes for hosts that send report messages and deletes the group membership of hosts that do not.

D.A receiver host periodically sends a Report message.

A.DD packets contain headers of all LSAs for periodic LSDB synchronization between OSPF neighbors.

B.The intervals at which two routers send Hello messages must be consistent; otherwise, cannot be established relationships between neighboring devices.

C.Hello messages are used as a form of greeting to discover other routers on its networks and establish relationships between neighboring devices. On broadcast or NBMA networks, Hello messages can also be used to elect a DR or a BDR.

D.DD packets describe the summary LSDB information by carrying LSA headers.

A.Network LSAs are flooded in the entire AS.

B.DR uses Network LSAs to describe routers that have established adjacency with it in the network,

C.Only the router which is connected to NBMA or Broadcast Network may generate Network LSAs.

D.Network LSAs are generated by ABR.

A.BGPID

B.Holder timer

C.Local AS number

D.Current peer status

E.Keepalive timer