SMTP的默认端口为（1），其作用是（2）。 空白（2）处应选择（）

A:发送邮件 B:接收邮件 C:浏览网页 D:QQ聊天

ARP攻击造成网络无法跨网段通信的原因是（1）。可以使用（2）命令清除受攻击影响的ARP缓存。 空白（1）处应选择（）

A:发送大量ARP报文造成网络拥塞 B:伪造网关ARP报文使得数据包无法发送到网关 C:ARP攻击破坏了网络的物理连通性 D:ARP攻击破坏了网关设备

ARP攻击造成网络无法跨网段通信的原因是（1）。可以使用（2）命令清除受攻击影响的ARP缓存。 空白（2）处应选择（）

A:arp-s B:arp-d C:arp-all D:arp-a

在某PC上运行ipconfig/all命令得到如下结果，本机IP地址的租约期为（1）小时，该PC访问Web网站时最先查询的DNS服务器为（2）。 空白（1）处应选择（）

A:8 B:12 C:24 D:48

在某PC上运行ipconfig/all命令得到如下结果，本机IP地址的租约期为（1）小时，该PC访问Web网站时最先查询的DNS服务器为（2）。 空白（2）处应选择（）

A:215.155.3.190 B:8.8.8.8 C:252.117.112.3 D:152.50.255.1

PC1接入Internet的拓扑如下图所示，其中Serverl为Web服务器，则PC1的Internet协议属性参数的配置中，IP地址可能为（1），默认网关为（2）。 空白（1）处应选择（）

A:61.248.12.34/27 B:61.248.12.65/26 C:61.248.12.62/27 D:203.174.56.171/30

PC1接入Internet的拓扑如下图所示，其中Serverl为Web服务器，则PC1的Internet协议属性参数的配置中，IP地址可能为（1），默认网关为（2）。 空白（2）处应选择 （）

A:61.248.12.34/27 B:61.248.12.65/26 C:61.248.12.62/27 D:203.174.56.171/30

A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication, TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocolis to create a  (2) and error-control mechanism at the transport level. TCP uses a sliding(3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve(4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends  (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

A:numbers B:connections C:diagrams D:resources

A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication, TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocolis to create a  (2) and error-control mechanism at the transport level. TCP uses a sliding(3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve(4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends  (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

A:procedure B:function C:route D:flow

A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication, TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocolis to create a  (2) and error-control mechanism at the transport level. TCP uses a sliding(3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve(4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends  (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

A:path B:window C:frame D:diagram