多项选择题 You are attempting to troubleshoot some problems within your local network.Which of the following are router IOS commands that can be used to troubleshoot LAN connectivity problems?（）

单项选择题 What command verifies connectivity between two hosts by sending and receiving ICMP echo messages?（）

单项选择题 A new Catalyst switch is connected to an existing switch using a crossover cable. As a result of this, what would the switch port link lights display?（）