You are the network administrator of an enterprise company that just deployed a global IP telephonyenvironment. In order to guarantee good voice quality，you asked your provider to implement QoS on the CE routers of your MPLS network. On your LAN，you have also deployed QoS.Users，however，keep complaining about bad voice quality，and the provider does not see matches on the DSCP values that you have asked him to match upon. What is most likely the problem？（）

单项选择题YouarethenetworkadministratorofaLayer3switchednetwork.UsersinoneVLANarecomplainingthataccesstotheserverVLANisveryslowfromtimetotime.TrafficinthelocalVLANworkswithoutanyissue，andusersinotherVLANsdonothaveanycomplainttoreachtheserverVLAN.Whatismostlikelythecauseofthisissue？（）

A.routing issue
B.denial-of-service attack
C.MAC flooding
D.spanning-tree recalculation
E.Layer 2 loop
F.ARP spoofing attack

单项选择题Youaredeployingtwocoreswitches，oneineachbuilding，50kmawayfromeachother.Thecross-connectionbetweenthemwillbeaLayer22-gigabitEtherChannelwithan802.1Qtrunk.Youconfigureditcorrectlybutthelinkdoesnotcomeup.Theportisinthe adminup state，andthelineprotocolisinthe down state.ThefiberlinkisOK.Whatwouldbethemostlikelyreasonforthelinknottocomeup？（）

A. The switches are not the same model
B. You are not using the correct SFP
C. You are not using correct optical media converters
D. Configuration should be modified， because the distance is longer

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.