Q: 1
Exhibit
You are advertising a summary route that represents your local network (172.20.0.0716) to both ISP
A and ISPB. You want to influence all traffic sent to you from ISP C to go through R2.
How would you accomplish this task?
You are advertising a summary route that represents your local network (172.20.0.0716) to both ISP
A and ISPB. You want to influence all traffic sent to you from ISP C to go through R2.
How would you accomplish this task?Options
Discussion
Had something just like this on my exam. The trick is to use AS path prepending from R2 so ISP C sees a longer path if coming via R1, making traffic favor the R2 route. Option C lines up with that. Anyone see it differently?
I thought B might work since changing the local preference to 250 on R1 would prioritize that path, but I realize now that's only effective inside your own AS. If you want ISP C to pick R2, local preference on R1 won't actually influence their decision. Still, I assumed increasing it would somehow help influence upstream choices. Anyone else pick B at first?
Had something like this in a mock and picked C. AS path prepending on R2 is how you get ISP C to route traffic through that link instead. Pretty sure that's what Juniper wants here, but open to corrections.
C , saw similar scenario flagged as correct in a practice exam.
A I think changing local preference on R1 (B) would push inbound traffic through that path, since higher local pref is preferred. Not totally sure if that affects ISP C though, but seems logical to me. Open to other takes.
Yeah, C makes the most sense. If you want to steer incoming routes from ISP C via R2, you need to manipulate the AS path by prepending your AS on R2's outbound route towards ISP 2. Pretty sure that's the usual BGP trick for this scenario.
C here. The distractor is A, but to influence inbound from ISP C you need to prepend on R2 when sending to ISP 2, not on R1. Seen similar logic in practice exams, pretty sure this is the right call.
These BGP questions are always tricky with the path engineering. C
C vs B here-C is correct. Prepending your AS number on R2 influences how *external* networks like ISP C see your routes, since AS path length is a key inbound metric. Local pref (B) only matters inside your own AS, so it wouldn't impact ISPs upstream. That's a subtle difference, but it flips the answer. Let me know if anyone disagrees.
I went with B for this one. Raising local preference on R1 to 250 seems like it would make traffic favor that path, and I've seen similar tips in some BGP labs. If we're just trying to steer traffic coming into our AS from ISP C, I figure bumping up the local pref is enough. Not 100% but that was my logic. Someone correct me if I'm off here?
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