单项选择题
A.255.255.128.0 （11111111.11111111.10000000.00000000） B.255.255.192.0 （11111111.11111111.11000000.00000000） C.255.255.224.0 （11111111.11111111.11100000.00000000） D.255.255.240.0 （11111111.11111111.11110000.00000000）
ADNSserverforalargenetworkisexperiencingperformanceprob...
单项选择题A DNS server for a large network is experiencing performance problems. Which of the following options is the best solution to fix the problem？（）
A.Enable NIS B.Purchase a larger server C.Use /etc/hosts on all of the systems D.Create secondary name servers throughout the network
AnIPaddressis198.37.16.23.Whichofthefollowingrouter’sIP...
单项选择题An IP address is 198.37.16.23. Which of the following router’s IP addresses should be used to route traffic to the 193.130.56.0 network？（）
A.193.130.56.0 B.198.37.16.15 C.198.130.16.15 D.198.130.56.15
Ahostisexpectedtobeamailrelayorreceivingendpoint.Whicho...
单项选择题A host is expected to be a mail relay or receiving endpoint. Which of the following daemons should be listening for connections on port 25？（）
A.ftpd B.imapd C.pop3d D.sendmail
