Huawei H12-821_V1.0 Exam - Topic 2 Question 77 Discussion

Actual exam question for Huawei's H12-821_V1.0 exam

Question #: 77
Topic #: 2

On the OSPF network shown in the figure, R1, R2, and R3 run OSPF, and R1 advertises four VPN routes to OSPF. A filter-policy needs to achieve the following goal: R1's and R3's routing tables contain the routes to 192.168.3.0/24, but R2's routing table does not. Which of the following filter-policies cannot meet this requirement?

AA filter-policy on R2 for filtering received routes

BA filter-policy on R2 for filtering the routes to be advertised

CA filter-policy on R1 for filtering the routes to be imported

DA filter-policy on R1 for filtering the imported routes to be advertised

Show Suggested Answer

Suggested Answer: C

Goal Analysis:

Requirement:

The route to 192.168.3.0/24 must exist in R1's and R3's routing tables.

The route must not exist in R2's routing table.

This requires filtering to ensure the route is either:

Blocked on R2's routing table (via filtering on R2), or

Blocked before it is advertised to R2.

Analysis of Each Option:

Option A (Filter-policy on R2 for filtering received routes):

Applying a filter-policy on R2 to filter received routes will block the route from entering R2's routing table but still allow it to propagate to R3.

This meets the requirement.

Option B (Filter-policy on R2 for filtering the routes to be advertised):

Blocking the advertisement of routes from R2 to other routers does not affect the routes received by R2 itself.

This does not meet the requirement but does not affect the propagation to R3.

This is valid if the received route is blocked.

Option C (Filter-policy on R1 for filtering the routes to be imported):

If the route is filtered on R1 during the import phase, the route will not exist in R1's routing table and thus cannot be advertised to either R2 or R3.

This fails to meet the requirement because the route must exist in R1's and R3's routing tables.

Option D (Filter-policy on R1 for filtering the imported routes to be advertised):

Filtering routes on R1 before advertising to R2 will prevent R2 from receiving the route but allow R1 to advertise the route to R3.

This meets the requirement.

Correct Option:

C (Filter-policy on R1 for filtering the routes to be imported): This will prevent the route from existing in both R1 and R3, violating the stated requirement.

HCIA-Datacom Study Guide, Chapter: OSPF Route Filtering

Huawei OSPF Configuration and Filtering Methods

by Sarina at Jan 24, 2025, 07:19 AM

Limited Time Offer

25%

Off

Get Premium H12-821_V1.0 Questions as Interactive Web-Based Practice Test or PDF

Contribute your Thoughts:

Submit Cancel

Buck

3 months ago

Filtering on R2 for received routes is pointless here.

upvoted 0 times

...

Darci

3 months ago

I think option C might also be problematic, not sure though.

upvoted 0 times

...

Lura

3 months ago

Wait, how does filtering on R1 affect R2? Seems off.

upvoted 0 times

...

Whitley

3 months ago

Totally agree, option B is the one that can't work.

upvoted 0 times

...

Jenise

4 months ago

R1 advertises the routes, so filtering on R2 won't help.

upvoted 0 times

...

Delisa

4 months ago

I’m leaning towards option C because filtering on R1 for imported routes seems like it wouldn’t stop R2 from getting the routes.

upvoted 0 times

...

Rex

4 months ago

I practiced a similar question where filtering on the router receiving the routes was key. I feel like option B could also be a candidate for not achieving the goal.

upvoted 0 times

...

Darnell

4 months ago

I'm not entirely sure, but I remember something about filtering on the advertising side. Could option D be the one that doesn't meet the requirement?

upvoted 0 times

...

Hester

4 months ago

I think option A might not work because filtering on R2 would still allow R1 to send the routes to R2, right?

upvoted 0 times

...

Adelle

5 months ago

Yes, that makes sense to me. Option B seems like the most targeted approach to achieve the desired outcome.

upvoted 0 times

...

Mi

5 months ago

Based on the options provided, I think the answer is B. A filter-policy on R2 for filtering the routes to be advertised would be the only way to prevent R2 from receiving the 192.168.3.0/24 route while allowing R1 and R3 to have it.

upvoted 0 times

...

Winfred

5 months ago

I'm a bit confused about the different filter-policy options. Which one would be the best approach to meet the given requirement?

upvoted 0 times

...

Skye

5 months ago

Okay, let's think this through step-by-step. We need to prevent R2 from receiving the 192.168.3.0/24 route, while allowing R1 and R3 to have it. That means we need to filter the routes on R2.

upvoted 0 times

...

Dudley

5 months ago

This question seems straightforward, but I want to make sure I understand the requirements correctly before attempting to solve it.

upvoted 0 times

...

Carman

5 months ago

Ah, I see now. The question is asking which filter-policy cannot meet the requirement, so I'll need to carefully evaluate each option to determine the one that won't work.

upvoted 0 times

...

Misty

5 months ago

I think I've got it! The filter-policy needs to be applied on R2 to filter the routes being advertised, not the routes being received. That should do the trick.

upvoted 0 times

...

Cyril

5 months ago

I'm a bit confused by the wording of the question. Does the filter-policy need to be applied on R1, R2, or R3? I'll need to re-read the question carefully.

upvoted 0 times

...

Maxima

5 months ago

Okay, let me think this through. I believe the key is to identify where the filter-policy needs to be applied to achieve the desired outcome on R2's routing table.

upvoted 0 times

...

Lezlie

5 months ago

Hmm, this seems like a tricky one. I'll need to carefully analyze the network topology and OSPF configuration to determine the best approach.

upvoted 0 times

...

Marla

12 months ago

Option B all the way! It's like hiding the cookies from the cookie monster - you gotta keep them out of sight, am I right?

upvoted 0 times

Marshall

11 months ago

Yeah, just like hiding cookies from the cookie monster, we need to filter the routes to be advertised on R2.

upvoted 0 times

...

Martina

12 months ago

Yeah, just like hiding cookies from the cookie monster. Can't let R2 see those routes to 192.168.3.0/24.

upvoted 0 times

...

Reuben

12 months ago

I agree, option B seems like the best choice to keep those routes hidden from R2.

upvoted 0 times

...

Frankie

12 months ago

I agree, option B seems like the way to go. Gotta keep those routes hidden from R2.

upvoted 0 times

...

Kerry

1 year ago

I agree with Craig. So, the correct answer should be C.

upvoted 0 times

...

Craig

1 year ago

But if R1 filters the routes to be imported, then R2's routing table won't have the route to 192.168.3.0/24.

upvoted 0 times

...

Shizue

1 year ago

Hmm, this is a tricky one. I'd better double-check the topology and requirements to make sure I'm not missing anything. Maybe I should ask the teacher for a hint.

upvoted 0 times

...

My

1 year ago

I'm not sure about this one. Option A could also work, but it might be more complicated to set up. Option B seems like the simplest solution.

upvoted 0 times

Jackie

11 months ago

I agree, Option B is probably the best choice for this scenario.

upvoted 0 times

...

Alex

11 months ago

Yeah, Option B does seem like the easiest way to achieve the goal.

upvoted 0 times

...

Luisa

12 months ago

I think Option B is the simplest solution.

upvoted 0 times

...

Lindy

12 months ago

Option A could work, but it might be more complicated to set up.

upvoted 0 times

...

Bobbye

1 year ago

No, I believe it's C.

upvoted 0 times

...

Craig

1 year ago

I think the answer is A.

upvoted 0 times

...

Fairy

1 year ago

Option B seems like the right choice here. If we need to prevent R2 from seeing the 192.168.3.0/24 routes, then we have to filter the routes being advertised from R1 to R2.

upvoted 0 times

Shanice

1 year ago

Yes, that makes sense. By applying a filter-policy on R2 for filtering the routes to be advertised, we can achieve the goal of not having R2 see the 192.168.3.0/24 routes.

upvoted 0 times

...

Vallie

1 year ago

I agree, option B is the correct choice. Filtering the routes to be advertised from R1 to R2 will prevent R2 from seeing the 192.168.3.0/24 routes.

upvoted 0 times

...