多项选择题
A. to ensure a loop-free topology
B. to protect against user-side loops
C. when a VLAN spans access layer switches
D. for the most deterministic and highly available network topology
E. because of the risk of lost connectivity without Spanning Tree Protocol
多项选择题 WhichtwooftheseareadvantagesofplacingtheVPNdeviceintheDMZonthefirewall？（）
单项选择题 Inwhichtunnel-lessVPNtopologydogroupmembersregisterwithakeyserverinordertoreceivethesecurityassociationnecessarytocommunicatewiththegroup？（）
单项选择题 Inabasee-Commercemoduledesign，whichroutingstatementiscorrect？（）