Which of the following commands should be used to check whether a system dump is valid and readable?（）

单项选择题Ifasystemadministratorwantstoshowonlyadiskreportfordisk2,attwosecondintervals,whatisthecorrectcommandtorun?（）

A. iostat disk1 1 
B. iostat -d disk1 2 
C. iostat disk2 1 
D. iostat -d disk2 2

单项选择题Whichiostat%iowaitminimumthresholdindicatesapossibleI Obottleneck?（）

A.20% 
B.40% 
C.60% 
D.80%

单项选择题Whichcommandrecordsthepathtakenbynetworkpacketsbetweenasourceanddestinationsystem?（）

A. traceroute 
B. netstat -p 
C. ping 
D. netstat -rn

单项选择题Whichofthefollowingcommandsshouldbeusedtoobservethenumberofsystemcallspersecond?（）

A. sar 
B. iostat 
C. svmon 
D. vmstat

单项选择题AllofthefollowingtypesofstatisticsarereportedbytheiostatcommandtoolEXCEPT:（）.

A. Free memory
B. CPU statistics 
C. Disk statistics 
D. Terminal statistics