802题！考CCNA的进，也请NP和IE的指导下

来源：百度知道 编辑：UC知道 时间：2024/06/15 20:25:41
TESTINSIDE的题

关于这个图
看R1的配置信息
其他路由器协议，接口配置正确
我知道R1的默认路由配置错误

请问下为什么R2不能和R1建立邻居关系？ 而PASS4SURE说当R2收到路由表里没有条目的包时发送给R1而R1又发回R2然后形成环路 既然不能建立邻居关系 R2应该丢包才对 为什么又形成环路呢？

请不要复制长篇大论或别人的东西，如果回答得好我可以加分！谢谢
A. Router R2 will not form a neighbor relationship with R1.
B. Router R2 will obtain a full routing table, including a default route, from R1.
C. R2 will obtain OSPF updates from R1, but will not obtain a default route from R1.
D. R2 will not have a route for the directly connected serial network, but all other directly
connected networks will be present, as well as the two Ethernet networks connected to R1.
Answer: A
答案是A 难道答案错了
B是正确答案吗？

是这个样子的。R1路由表里没有包的路径，所以他走默认理由，从s0/0口出去，包会路由到R2.因为R1里面有default-information originate。R2会认为有一条默认路由到R1。所以他又会把包弄回R1。之后r1 又把包弄到R2。如此类推。形成loop。据说在实际环境 是不会形成loop。你感兴趣可以自己做下
Assume that all router interfaces are operational and correctly configured. In addition, assume that OSPF has been correctly configured on router R2.
How will the default route configured on R1 affect the operation of R2?
A. Any packet destined for a network that is not directly connected to router R1 will be dropped.
B. Any packet destined for a network that is not directly connected to router R2 will be dropped immediately.
C. Any packet destined for a network that is not directly connected to router R2 will be dropped immediately because of the lack of a gateway on R1.
D. The networks directly connected to router R2 will not be able to communicate with the 172.16.100.0, 172.16.100.128, and 172.16.100.64
subnetworks.
E. Any packet destined for a network that is not referenced in