单项选择题 Theclientconnectedtothedatabaseturnsoffhisorhermachinewithoutexitingfromaconnectiontothedatabase.Whichtypeoffailureisthis？（）

单项选择题 You configured automatic archive logging for the database. On the next startup the database runs for a while， but then hangs. After checking the alert log， you determine that all the online redo logs need archiving.  Which step was skipped when you set up automatic archive log？（）

单项选择题 A client/server application has been configured to use local naming. The client and server run on separate machines. When the client tries to connect， it receives a TNS error. By carefully examining the environment， a tnsnames.ora is found only on the Oracle server machine， among other things. After copying this tnsnames.ora onto the client machine， the client is able to connect to the server.  Which statement is true？（）