简答题 what is URPF？

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

问答题whatistheNAToverloading？

问答题what does three entries of the diagram mean？ 给一张show ip bgp如下

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.