An  administrator  runs  mktcpip  aixhost  172.168.0.50  enO  to  change  the  network  address，  but  the  command  hangs  for  an  extended  period  of  time.  
Which  of  the  following  is  the  most  likely  cause  of  the  problem（）

单项选择题AnadministratorreceivedacallfromauserwhosePCcrashedwhileusingvitoeditafile.Theuserwantstheeditedfileback.Whereshouldtheadministratorlookforthefile（）

A./tmp
B./var/preserve
C./var/tmp/$USER
D.$HOME/.vi

单项选择题UnderwhichofthefollowingcircumstancesmustaJFSfilesystembeusedinsteadofaJFS2filesystem（）

A.filesystem will contain 100GB files
B.filesystem resides on a 32-bit system
C.filesystem contains a large number of small files
D.filesystem compression is required

单项选择题Anadministratorneedstochangeasystem’srunlevelfromlevel2tolevel3.Whatistheappropriatemethodtoaccomplishthis（）

A.Use the reboot command.
B.Edit the /etc/reboot file and reboot the system.
C.Edit /etc/.init.state file and reboot the system.
D.Use the telinit command

单项选择题Anadministratorneedstobeabletolistthenumberandsizeofbackupsetsonatape.Whichofthefollowingproceduresaccomplishthis（）

A.Use the tcopy /dev/rmtO.l until an end-of-tape error notification is received.
B.Use the cpio -idmv < /dev/rmtO.l until an end-of-tape error notification is received.
C.Use the tar -tvf /dev/rmtO.l repeatedly until an end-of-tape error notification is received.
D.Use the dd if=/dev/rmt0.1 bs=128k count=EOT until an end-of-tape error notification is received.

单项选择题Auserwantstobepermanentlyaddedtothedbagroup.Whichofthefollowingcommandsorprocessescanbeusedtoaccomplishthis（）

A.chgrp
B.chuser
C.edit /etc/user
D.edit /etc/security/group