CCNA系列认证单项选择题每日一练(2020.04.27)

单项选择题
Which Cisco Catalyst switches fit in the access area？（）
A. Cisco Catalyst 2900 Series，Catalyst 7300 Series，and Catalyst 8000 Series
B. Cisco Catalyst 2900 Series，Catalyst 3700 Series，and Catalyst Series
C. Cisco Catalyst 2700 Series，Catalyst 7300 Series，and Catalyst 8000 Series
D. Cisco Catalyst 2700 Series，Catalyst 3700 Series，and Catalyst4500 Series
单项选择题
You have a network that supports VLSM and you need to reduce IP address waste in your point to point WAN links. Which of the masks below would you use?（）
A./38
B./30
C./27
D./23
E./18
F./32
单项选择题
Which command shows your active Telnet connections?（）
A. show session
B. show cdp neighbors
C. show users
D. show queue
单项选择题
A receiving host computes the checksum on a frame and determines that the frame is damaged.The frame is then discarded.At which OSI layer did this happen?（）
A. session
B. network
C. Physical
D. data link
E. Transport
单项选择题
Which protocol is an open standard protocol framework that is commonly used in VPNs,to provid secure end-to-end communication?（）
A. L2TP
B. IPsec
C. PPTP
D.RSA