单项选择题
A.after broken links are re-established
B.in an improperly implemented redundant topology
C.when upper-layer protocols require high reliability
D.during high traffic periods
E.when a dual ring topology is in use
单项选择题 Whichcommandsetsandautomaticallyencryptstheprivilegedenablemodepassword？（）
单项选择题 Whichstatementistrue？（）
多项选择题 A company is installing IP phones. The phones and office computers connect to the same devicE.To ensure maximum throughput for the phone data, the company needs to make sure that the phone traffic is on a different network from that of the office computer data traffiC.What is the best network device to which to directly connect the phones and computers, and what technology should be implemented on this device? （）