Which of the following applications is MOST likely to require QoS to ensure proper functionality?（）

单项选择题A technician is troubleshooting a network connectivity issue. Given the following abbreviated trace route output: Which of the following is MOST likely occurring?（）

A. Switching loop
B. Broadcast storm
C. IP conflict
D. Routing loop

单项选择题At which of the following layers does the TCP protocol operate?（）

A.Layer 1
B.Layer 4
C.Layer 6
D.Layer 7

单项选择题A user on a network cannot access any network resources. The link light on the computer showsthat a connection is present. Which of the following is the MOST likely cause of the problem?（）

A. The wrong cable type has been used.
.B. IDS has shut down the computer's switch port.
C. The port on the switch is configured incorrectly
D. Spanning tree protocol was implemented.

单项选择题A company wants to secure access to its internal wireless network. The company wants to use themost secure means to access the network. Which of the following is the BEST choice for wireless security in this situation?（）

A. WEP encryption
B. Channel rotation
C. Disable SSID
D. WPA encryption

单项选择题Which of the following WAN technologies modulates 24 channels into a 1 5Mbps signal?（）

A.ISDN
B.PSTN
C.OC-2
D.T1