What s the default stratum clock on a Cisco router，when you see the key word "master" configured on the NTP line？（）

多项选择题ThecoreofanetworkhasfourroutersconnectedinasquaredesignwithGigabitEthernetlinksusing 30subnets.Thenetworkisusedtocarryvoicetrafficandotherapplications.Convergencetimeistakingmorethanexpected.WhichthreeactionswouldyoutaketoimproveOSPFconvergencetime？（）

A.Increase MTU of the interfaces to accommodate larger OSPF packets.
B.Change the network type to point-to-point on those links.
C.Reduce SPF initial timer.
D.Increase hello interval to avoid adjacency flapping.
E.Enable OSPF

单项选择题UnicastReversePathForwardingcanperformalloftheseactionsexceptwhichone？（）

A.examine all packets received to make sure that the source addresses and source interfaces appear in the routing table and match the interfaces where the packets were received
B.check to see if any packet received at a router interface arrives on the best return path
C.combine with a configured ACL
D.log its events，if you specify the logging options for the ACL entries used by the unicast rpf command
E.inspect IP packets encapsulated in tunnels， such as GRE

单项选择题WhichofthesestatementsaccuratelyidentifieshowUnicastReversePathForwardingcanbeemployedtopreventtheuseofmalformedorforgedIPsourcesaddresses？（）

A.It is applied only on the input interface of a router.
B.It is applied only on the output interface of a router.
C.It can be configured either on the input or output interface of a router.
D.It cannot be configured on a router interface.
E.It is configured under any routing protocol process.

多项选择题WhichtwoofthesestepsareminimumrequirementstoconfigureOSPFv3underIPv6？（）

A.Configure a routing process using the command ipv6 router ospf [process-id].
B.Add the network statement for the interfaces on which OSPF will run.
C.Configure OSPF on the interface that it will run on.
D.Use the passive-interface command on the interfaces on which OSPF should not run.
E.Enable routing.

单项选择题TwoBGPpeersconnectedthrougharoutedfirewallareunabletoestablishapeeringrelationship.Whatcouldbethemostlikelycause？（）

A.BGP peers must be Layer 2-adjacent.
B.EBGP multihop is not configured.
C.The firewall is not configured to allow IP protocol 89.
D.The firewall is not configured to allow UDP 179.