You are deploying two core switches， one in each building， 50 km away from each other. The cross-connection between them will be a Layer 2 2-gigabit EtherChannel with an 802.1Q trunk. You configured it correctly but the link does not come up. The port is in the "admin up" state， and the line protocol is in the "down" state. The fiber link is OK. What would be the most likely reason for the link not to come up？ （）

多项选择题YourcompanyisresearchinganewapplicationthatrunsoverIPv6，butpartofitmuststillhaveIPv4support.YourcompanyusesatraditionalIPv4network.YourplanisnottorunIPv6overthewholenetwork，buttosegmentpartsofthenetworkoreventooperatesimultaneouslywithIPv6andIPv4.YoumustmakeabriefpresentationaboutIPv6technologytotheboardoftechnicaldirectors.Whichthreeoftheseitemscouldbepartofyourpresentation？（）

A. Tunnel IPv6 over IPv4 to connect far-end IPv6 networks
B. Explain why configuring IPv4 and IPv6 at the same time over the same LAN interface is not possible
C. Explain why configuring IPv4 and IPv6 at the same time over the same LAN interface is possible
D. What is the meaning of EUI-64 and how does it work？
E. Tunnel IPv4 over IPv6 to connect far-end IPv4 networks.

单项选择题WhatisacharacteristicofNetworkTimeProtocol？（）

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？（）

A. EtherChannel is only available in Cisco equipment. 
B. The customer side is supposed to be running PAgP, which is a Cisco standard. 
C. PAgP is not an IEEE standard. VRRP should be used. 
D. The configuration on switch1 needs to be modified to use LACP. 

多项选择题WhichthreeprotocolsshouldbeexplicitlymanagedbyusingControlPlanePolicingonanInternetborderrouter？（）

A.LDAP
B.ICMP
C.RTP
D.BGP
E.SSH
F.RDP

多项选择题Whichtwostatementsaretrueaboutbandwidthguarantee？（）

A.When congestion is present，the priority command doesn’t allow exceeding the allocated rate
B.When congestion isn’t present，the priority command doesn’t allow exceeding the allocated rate
C.When congestion is present，the priority command allows exceeding the allocated rate
D.When congestion isn’t present，the priority command allows exceeding the allocated rate