A. MeshB. Point to pointC. Point to multipointD. RingA ……

单项选择题An administrator attempts to open a web page and sees the following error: Error 404: Page not found. The administrator then uses the ping command and finds that the default gateway cannot be pinged. At which of the following layers does the problem MOST likely reside?（）

A.Layer 1
B.Layer 4
C.Layer 5
D.Layer 7

单项选择题The technician notices that one of the wires in a CAT5 cable is cut in half. Which of the followingconnectivity issues did the technician discover?（）

A.Open pairs
B.Attenuation
C.Crosstalk
D.Interference

单项选择题Which of the following cable types is intended to be used on short distances and is immune to anytype of interference?（）

A. Singlemode fiber
B. Multimode fiber
C. Shielded twisted pair
D. Unshielded twisted pair

单项选择题Which of the following protocols requests membership to a multicast group?（）

A.IGMP
B.SNMP
C.SMTP
D.ICMP

单项选择题A small amount of spoofed packets are being sent across a network and a large amount of reply packets are being sent back to the network resource. Which of the following BEST describes this security threat?（）

A.Worm
B.Smurf
C.Logic Bomb
D.Man-in-the-middle