多项选择题 Whichthreecharacteristicsaretrueaboutvoicetrafficinthecampusnetwork？（）

单项选择题 Refer to the exhibit. The command spanning-tree guard root is configured on interface Gi0/0 on both switch S2 and S5. The global configuration command spanning-tree uplinkfast has been configured on both switch S2 and S5. The link between switch S4 and S5 fails.  Will Host A be able to reach Host B？ （）

单项选择题 On an Aironet card， LED 0 and LED 1 are blinking alternately.  What does this indicate？ （）