What are two reasons an IBGP learned route would be hidden? (Choose two.)
What are two reasons an IBGP learned route would be hidden? (Choose two.)
An IBGP learned route can be hidden for two primary reasons. First, a route can be rejected by an export policy, which happens after it has been imported into the routing table but before it is advertised to other peers. Second, a route with an empty AS path can also be hidden. AS paths are necessary to prevent routing loops and ensure proper path selection; hence, an empty AS path would make the route invalid and hidden. Other factors, like flap damping and the next hop being the local device, typically affect EBGP rather than IBGP routes.
A could not be correct because: Because routing consistency within an AS is important, do not apply flap damping to internal BGP (IBGP) routes. (If you do, it is ignored.) https://www.juniper.net/documentation/en_US/junos/topics/topic-map/bgp-flap-damping.html
same link: There is an exception that rule. Starting in Junos OS Release 12.2, you can apply flap damping at the address family level. In a Junos OS Release 12.2 or later installation, when you apply flap damping at the address family level, it works for both IBGP and EBGP. By default, route flap damping is not enabled. Damping is applied to external peers and to peers at confederation boundaries. A&B
Even if for some reason you think A is incorrect. C and D are the most incorrect.
Leaning towards B & C BGP route flapping describes the situation in which BGP systems send an excessive number of update messages to advertise network reachability information. BGP flap damping is a method of reducing the number of update messages sent between BGP peers, thereby reducing the load on these peers, without adversely affecting the route convergence time for stable routes. Flap damping reduces the number of update messages by marking routes as ineligible for selection as the active or preferable route. Marking routes in this way leads to some delay, or suppression, in the propagation of route information, but the result is increased network stability. You typically apply flap damping to external BGP (EBGP) routes (routes in different ASs). You can also apply flap damping within a confederation, between confederation member ASs. Because routing consistency within an AS is important, do not apply flap damping to internal BGP (IBGP) routes. (If you do, it is ignored.)
I was wrong as an export policy is applied after the RIB and not before the correct scheme being confederation boundary. The process in BGP is Route sent from peer ->> Adj-Rib-in ->>>import policy ->>> route selection ->>> RIB-Local Which makes the import no-export plausible for the routes received from R1 as you are preventing the propagation of the route within AS FOR routes you are sending the path is : RIB-local ->>> export policy ->>> Adj-RIB ->>> peer Then the no advertise export makes sense ! You should check JNCIP free courses on juniper learning You are asking peers in the same AS not to advertise to other AS ; the routes will be contained only in the AS
It’s AB C would be correct if it was an import policy
A and B are correct