单项选择题 Please match the Cisco STP enahancement term to its definition.（） (1) BPDU guard (2) PortFast (3) BackboneFast (4) Loop guard (5) Root guard (a) shuts down a port that receives a BPDU when enabled (b) cuts convergence time by mas-age for indirect failure (c) prevents the aliernate or root port from being designated in absence of BPDUs (d )causes Layer 2 LAN interface access port to immediately enter the forwarding state (e) helps prevent bridging loops due to jni-directional link failures on point-to-point links

单项选择题 You are the Cisco Network Designer . Which is not major scaling, sizing, and performance consideration for an IPsec design?（）

单项选择题 You are the network consultant from pass4sure.com. One of your customer has six sites, three of which process a large amount of traffic among them. He plans to grow the number of sites in the future. Which is the most appropriate design topology?（）