The OSPF RFC 3623 Graceful Restart feature allows you to configure IETF NSF in ultivendor networks. When using OSPF Graceful Restart，which mechanism is used tocontinue forwarding packets during a switchover？（）

单项选择题Whatkeywordsdoyouneedtotheaccess-listtoprovidetotheloggingmessagelikesourceaddressandsourcemacaddress？（）

A.Log
B.Log-input
C.Log-output
D.Logging

单项选择题Whiledeployinganewswitch，youaccidentlyconnectports3 12and3 18together，creatingaloop.STPdetecteditandplacedport3 18inblockingmode.WhydidSTPnotplaceport3 12inblockingmodeinstead？（）

A.Port 3/12 was already up and forwarding before the loop was created.
B.Port priority is based on lowest priority and lowest port number.
C.You connected the wire on port 3/18 last.
D.None of the above， it is purely random.

单项选择题Youdeployednewfibersinyournetworktoreplacecopperspansthatweretoolong.Whilereconnectingthenetwork，youexperiencednetworkproblemsbecauseyoureconnectedwrongfiberstowrongports.Whatcouldyoudotopreventthistypeofprobleminthefuture，particularlywhenconnectingandreconnectingfiberpairs？（）

A.Only use fiber in pairs.
B.Configure root guard on your switches.
C.Do not use fiber but use copper.
D.Configure UDLD to prevent one-way link conditions.

单项选择题Whatarethemandatory，well-knownBGPattributes？（）

A.origin，AS-path，next-hop
B.AS-path，origin，MED
C.AS-path，origin，weight
D.AS-path，weight，MED

单项选择题YouuseOSPFasyournetworkroutingprotocol.YouusethecommandshowiprouteandyouseeseveralroutesdescribedasO，OIA，OE1，andOE2.Whatroutesareinyourarea？（）

A.O IA
B.O E1
C.O E2
D.O