按照域名系统的定义,域名www.sales.microsoft.com包含4个标识符,其中(1)是顶级域名,(2)是注册给组织或个人的二级域名。 空白(2)处应选择()
A. www
B. sales
C. microsoft
D. com
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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. ipconfig/renew
B. ipconfig/flushdns
C. netstat-r
D. arp-a
ARP请求消息是以()包发送的。
A. 单播
B. 组播
C. 广播
D. 任意播
在Excel中,若A1、A2、A3、A4、A5、A6单元格的值分别为90、70、95、55、80、60,在B1单元格中输入函数"=MIN(A1:A6)-MAX(A1:A6)",B2单元格中输入函数"=AVERAGE(A1:A6)",则B1和B2单元格的值分别为()。
A. 40和75
B. 40和65
C. -40和75
D. -40和65
One ofthe main resposibilities of ICMP is to report(1).Although technology has produced increasingly relaible transmission media, errors still exist and must be handled. IP is an (2) protocol. This means that error checking and error control are not a concern of IP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP does not (3) errors, it simply report them. Error correction is left to the higher-level potocols. Error messages are always sent to the original (4) because the only information available in the datagram about the route is the source and destination IP addresses. ICMP use the source IP address to sent the error massage to the source of the (5). 空白(2)处应选择()
A. reliable
B. unreliable
C. available
D. unavailable