求同学们解题 QUESTION 187

alvan1108

答案B我看明白的，但是D的作用是什么呢？求解析。
QUESTION 187
Having the above BGP peerings, select the two configurations for rtrB that will fulfill the following criteria:
-Will advertise all routes from rtrA to rtrD but not to rtrC

                               
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A. router bgp 2
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 route-map rtrA in
!
route-map rtrA permit 10
set community no-advertise
!
B. router bgp 2
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 route-map rtrA in
!
route-map rtrA permit 10
set community no-export
!
C. router bgp 2
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 route-map rtrA in
neighbor 3.3.3.3 remote-as 3
neighbor 3.3.3.3 route-map rtrC out
!
route-map rtrA permit 10
set community 5
!
route-map rtrC permit 10
match community 5
!
D. router bgp 2
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 route-map rtrA in
neighbor 3.3.3.3 remote-as 3
neighbor 3.3.3.3 route-map rtrC out
route-map rtrA permit 10
set community 5
!
route-map rtrC permit 10
match community 5
!
route-map rtrC permit 20
!
Correct Answer: BD

shaoyung