Which command enables RSTP on a switch?（）

单项选择题DNS servers provide what service?（）

A. they run a spell check on host names to ensure accurate routing
B. they map individual hosts to their specific IP address
C. they convert domain names into IP address
D. Given an IP address,they determine the name of the host that is…

单项选择题There are no boot system commands in a router configuration in NVRAM.What is the fallback sequence that router will use to find an ios during reload?（）

A. Flash,TFTP server,ROM
B. Flash,NVRAM,ROM
C. ROM,NVRAM,TFTP server
D. NVRAM,TFTP server,ROM
E. TFTP server,Flash,NVRAM

单项选择题Which command shows your active Telnet connections?（）

A. show session
B. show cdp neighbors
C. show users
D. show queue

单项选择题Which commands is necessary to permit SSH or Telnet access to a cisco switch that is otherwise configured for these vty line protocols?（）

A. transport type all
B. transport output all
C. transport preferred all
D. transport input all

单项选择题What is the OSPF default frequency,in seconds,at which a cisco router sends hello packets on a multi-access network?（）

A. 10
B. 40
C. 30
D. 20