请问这道题怎么理解？

sinkevin

Refer to the exhibit. From RouterA, a network administrator is able to ping the serial interface of RouterB
but unable to ping any of the subnets attached to RouterB. Based on the partial outputs in the exhibit, what
could be the problem?

A. EIGRP does not support VLSM.
B. The EIGRP network statements are incorrectly configured.
C. The IP addressing on the serial interface of RouterA is incorrect.
D. The routing protocol has summarized on the classful boundary.
E. EIGRP has been configured with an invalid autonomous system number.

keyhappy

考点在于EIGRP的自动路由汇总

啸傲～年华

ＥＩＧＲＰ默认自动汇总开启，故ＲｏｕｔｅｒＢ的三个子网在ＲｏｕｔｅｒＡ上汇总为１７２.１６.０.０／１６，Ｎｕｌｌ０，所以Ｐｉｎｇ的时候最长匹配到Ｎｕｌｌ０，也就是丢弃，所以ｐｉｎｇ不通

zh754267513

我看不懂应为！ 但是你不同我值到是什么原因！ 就是自动汇总！ 会在本地汇总一个172.16.0.0/16位的路由！当你平这个地址的时候，路由发现自己是直连的！就会发送到自己的路由上！不会网对端发！应为路由器也有点不信任外来的意思呵呵！所以在本地找，但是没有找到所以掉包了

aoklife

自动汇总惹的祸
就拿R1来说，R1认为它的左边直连有一个172.16.0.0的路由条目，而它的右面也是一个172.16.0.0的路由，当你发出ping 包的时候路由器当然就2了

sinkevin

我明白了，谢谢楼上朋友的解答