单项选择题
A.NTP updates are sent in the timezone they are collected in，and the syslog server will adjust based on the input time.
B.NTP authentication verifies the source，not the recipient.
C.NTP authentication requires that the recipient has multiple strata clocks to ensure accuracy.
D.Secure NTP can be configured to use SHA-1 hashing，since NTP is very insecure.
E.A stratum 0 clock should be configured at the core of every network，so it can connect to an accuratetime source.
单项选择题 Refer to the exhibit. You are setting up a 2-gigabit EtherChannel. Following IEEE standards， the exhibit shows your configuration in a local switch1. However， EtherChannel is not coming up. Which one of these statements could be a possible reason？（）
多项选择题 WhichthreeprotocolsshouldbeexplicitlymanagedbyusingControlPlanePolicingonanInternetborderrouter？（）
多项选择题 Whichtwostatementsaretrueaboutbandwidthguarantee？（）