OSPF邻接和毗邻

QUESTION NO: 18
You need to decide on the best routing protocol for the TestKing network and have narrowed your choices to IS-IS and OSPF. Which two are characteristics of the IS-IS protocol but not OSPF? (Select two)
下边哪两项是IS-IS协议的特性但不是OSPF的特性?(选2项)

A. IS-IS provides for network scalability by allowing the network to be separated into areas
B. IS-IS utilizes SPF algorithm
C. IS-IS supports demand circuit routing
D. IS-IS forms adjacencies with all neighbors
E. IS-IS supports three layers of hierarchical routing
F. IS-IS provides routing support for multiple network layer protocols

Answer: D, F

D就是你说的E

看下边IS-IS与OSPF的对比
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IS-IS与OSPF的比较
通过比较可以发现这两个协议大多数地方是相同的，同样的计算路由方法，同样使用链路状态数据库，同样的分层结构，尽管细节有点点不同。

1)网络类型
IS-IS 只定义了两种网络拓扑类型：broadcast和general topology。在Cisco路由器中链路分为point-to-point
和broadcast。
OPSF定义了5种网络类型：point-to-point、