1. [单选题]At which layer of the OSI model does the protocol that provides the information displayed by the "show cdp neighbors" command operate?
A. Transport
B. Physical
C. Application
D. Data link
E. Network
2. [单选题]OSI第二层数据封装完成后的名称是：()
A. 比特
B. 包
C. 帧
D. 段
