1. [单选题]OSI七层模型中，数据链路层的数据封装名称为（）
A. 比特
B. 帧
C. 包
D. 段
2. [单选题]两台路由器直连到一起，应该使用的线缆为（）
A. 交叉线缆
B. 直通线缆
C. 反转线缆
D. 任意线缆
3. [单选题]What is the purpose of the Spanning Tree Protocol (STP)?
A. To prevent routing loops
B. To create a default route
C. To provide multiple gateways for hosts
D. To maintain a loop-free Layer 2 network topology
E. To enhance the functions of SNMP
4. [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
5. [单选题]哪个ACL可允许主机10.220.158.10访问web服务器192.168.3.244()
A. access-list 101 permit tcp host 10.220.158.10 eq 80 host 192.168.3.224
B. access-list 101 permit tcp 10.220.158.10 0.0.0.0 host 192.168.3.224 0.0.0.0 eq 80
C. access-list 101 permit host 10.220.158.10 0.0.0.0 host 192.168.3.224 0.0.0.0 eq 80
D. access-list 101 permit tcp 10.220.158.10 0.0.0.0 host 192.168.3.224 eq 80
