以下给出的地址中，属于子网172.112.15.19/28的主机地址是（）。
A.172.112.15.17
B.172.112.15.14
C.172.112.15.16
D.172.112.15.31

下面RAID级别中，数据冗余能力最弱的是（　）
A.RAID5
B.RAID1
C.RAID6
D.RAID0

若采用后退N帧ARQ协议进行流量控制，帧编号字段为7位，则发送窗口最大长度为（　）。
A.7
B.8
C.127
D.128

某公寓在有线网络的基础上进行无线网络建设，实现无线入室，并且在保证网络质量的情况下成本可控，应采用的设备布放方式是（本题）。使用IxChariot软件，测试结果支持80MHz信道的上网需求，无线AP功率25mW，信号强度大于-65db。网络部署和设备选型可以采取的措施有以下选择：
①采用802.11ac协议
②交换机插控制器板卡，采用1+1主机热备
③每台POE交换机配置48口千兆板卡，做双机负载
④POE交换机做楼宇汇聚，核心交换机作无线网的网关
为达到高可靠性和高稳定性，选用的措施有（58）。
A.放装方式
B.馈线方式
C.面板方式
D.超瘦A.P方式

影响光纤熔接损耗的因素较多，以下因素中影响最大的是（64）。
A.光纤模场直径不一致
B.两根光纤芯径失配
C.纤芯截面不圆
D.纤芯与包层同心度不佳

Anytime a host or a router has an IP datagram to send to another host or router, it has the（　）address of the receiver. This address is obtained from the DNS if the sender is the host or it is found in a routing table if the sender is a router. But the IP data gram must be（　） in a frame to be able to pass through the physical network. This means that the sender needs the （　）address of the receiver. The host or the router sends an ARP query packet. The packet includes the physical and IP addresses of the sender and the IP address of the receiver. Because the sender does not know the physical address of the receiver, the query is（　） over the network.Every host or router on the network receives and processes the ARP query packet, but only the intended recipient recognizes its IP address and sends back an ARP response packet.The response packet contains the recipient's IP and physical addresses. The packet is（请作答此空） directly to the inquirer by using the physical address received in the query packet.

A. multicast
B. unicast
C. broadcast
D. multiple unicast