A. A subnet mask specifies the portion of an IP address……

单项选择题What is the purpose of a network mask?（）

A. It is used in conjunction with the wildcard mask to determine the number of hosts on a network
B. It is used to define which parts of the IP address are allocated to host addresses and network prefixes
C. It is used to hide subnets from external networks by masking the subnets with NAT
D. It is used to differentiate a network as a classful network or a classless network

单项选择题What is the purpose of a network mask?（）

A. It is used to identify the maximum hop count of a subnetwork.
B. It is used to identify an IP address as either private or public.
C. It is used to identify the network to which an IP address belongs.
D. It is used to identify the total number of bits present in an IP address.

单项选择题Which statement is true regarding an Ethernet collision domain?（）

A. If a router is used, the collision domain includes all devices connected to the router.
B. If a hub is used, the collision domain is limited to each device and the hub.
C. If a switch is used, the collision domain is limited to each device and the switch.
D. If a bridge is used, the collision domain includes all devices connected to the bridge.

多项选择题Two devices on an Ethernet segment sent frames at the same time causing a collision. Which two statements are true?（）

A. Both devices stop transmitting, wait a random period of time, verify the wire is idle, and re- transmit.
B. The device with the lowest MAC address is permitted to retransmit first.
C. The device with the lowest MAC address sends a jam signal to notify all other devices of the collision.
D. Both devices send a jam signal to notify all other devices of the collision.

多项选择题Which two statements are true regarding an Ethernet collision domain?（）

A. If a switch is used, the collision domain is limited to each device and the switch.
B. If a hub is used, the collision domain is limited to each device and the hub.
C. If a hub is used, the collision domain includes all devices connected to the hub.
D. If a switch is used, the collision domain includes all devices connected to the switch.