Windows系统中，在排除DNS域名解析故障时需要刷新DNS解析器缓存，使用的命令是（）

A:ipconfigenew B:ipconfig/flushdns C:netstat-r D:arp咀

用于显示TCP连接、计算机正在监听的端口、以太网统计信息的命令是（）

A:ipconfig B:nslookup C:netstat D:arp

SMTP建立的是（）连接，使用端口为（）。

SMTP建立的是（）连接。

A:TCP B:UDP C:ICMP D:HTTP

SMTP建立的是（）连接，使用端口为（）。

使用端口为（）

A:20 B:21 C:23 D:25

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

One ofthe main resposibilities ofICMP is to report（）

A:numbers B:functions C:strings D:errors

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

IP isan（）protocol.

A:reliable B:unreliable C:available D:unavailable

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

Howerver, ICMP doesnot （） errors, it simply report them.

A:correct B:conduct C:product D:connect

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

Error messages are always sent to the original（）because the only informationavailable in the datagram about the route is the source and destination IP addresses.

A:user B:destination C:source D:program

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

ICMP usethe source IP address to sent the error massage to the source ofthe（）.

A:datagram B:frame C:service D:protocol

[说明] 某公司内部局域网连接方式如图1-1所示。某Web服务器server1的域名为www.goodweb.com。 在主机host1的Windows命令行窗口输入tracertwww.goodweb.com命令后，测试到server1所经过的连接情况如图1-2所示。 为host2配置Internet协议属性参数。 IP地址：（范围）（1）； 子网掩码：（2）； 默认网关：（3）； （1）处应填（）。

115.3.3～215.115.3.126