为了与具体的物理传输介质无关，TCP/IP结构中并没有对最低两层做出规定。

A、对

B、错

Which command will purge the errorlog of all recorded occurrences of a given SRN?（）

A、errclear 0

B、errpt -r -j

C、errclear -j

D、errclear -k

通常所说的天线绝对高度指的是天线的挂高加上天线所在铁塔海拔与覆盖区域的差值。

A、对

B、错

A user can send e-mail， but cannot receive any e-mail. Which of the following settings should be verified in the e-mail account？（）

A、MAC address

B、TCP/IP address

C、POP Server settings

D、SMTP Server settings

An administrator is ordering a new Power 550. They will mirror rootvg and are concerned about single points of failure. Which of the following features should be ordered？（）

A、Dual I/O planar， dual disk drives， dual SCSI adapters

B、Dual disk drive enclosures， dual disk drives， extra media bay

C、Dual disk drive enclosures， dual disk drives and dual SCSI adapters

D、Dual I/O planar， extra media bay， dual disk drives

Which of the following commands will only provide a snapshot of average memory usage for a process？（）

A、 vmtune

B、 ps au

C、 iostat

D、 rmss -m