You have enabled backup optimization for the RMAN environment.Identify two criteria on which RMAN will skip the file, if it has already been backed up.（）
AThe data file backup is done with multiple channels
BThe data files is in the read-write mode after being backed up in the read only mode
CThe backup was taken after the data files was taken offline-normal or is in the read only mode
DThe data file backup complies with the back retention policy and the backup duplexing feature
主存储器有ROM和RAM，计算机突然停电后，存储信息就会丢失的是（）。
A、外存储器
B、只读存储器
C、寄存器
D、随机存储器
国际出入口信道提供单位、互联单位和接入单位必须建立（），健全管理制度，做好网络信息安全管理工作。
A、认证中心
B、网络管理中心
C、网络咨询中心
D、网络调度中心
局域网中，常用的网络传输介质有（）
A、双绞线
B、同轴电缆
C、光缆
D、电话线
现有： class Thread2 implements Runnable { void run（） { System.out.print（"go "）； } public static void main（String [] args） { Thread2 t2 = new Thread2（）； Thread t = new Thread（t2）； t.start（）； } } 结果为：（）
A、 go
B、 编译失败
C、 代码运行，无输出结果
D、 运行时异常被抛出
Which two statements in a source NAT configuration are true regarding addresses, rule-sets, or rules that overlap?（）(Choose two.)
AAddresses used for NAT pools should never overlap.
BIf more than one rule-set matches traffic, the rule-set with the most specific context takes precedence.
CIf traffic matches two rules within the same rule-set, both rules listed in the configuration are applied.
DDynamic source NAT rules take precedence over static source NAT rules.