Which statement is true regarding the IS-IS designated intermediate system (DIS)?
A . The DIS function is used only on broadcast or multi-access networks.
B . The DIS function is used on both broadcast and point-to-point link types.
C . On a broadcast network, adjacencies are formed only between the non-DIS nodes and the DIS to help reduce adjacency overhead.
D . IS-IS supports a backup DIS mechanism to provide rapid failover in the event of a DIS failure.
Answer: A