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  • Question 11 Route table

  • JimmyD

    Member
    November 24, 2022 at 10:18 pm

    In the question

    11. QUESTION

    A company is setting up a central Virtual Private Cloud named VPC A with one subnet and two VPC peering connections. The first connection is between VPC A and VPC B (pcx-aaaabbbb) and the second is between VPC A and VPC C (pcx-aaaacccc) . VPC B and VPC C both have one EC2 instance each with the same 10.0.0.10/32.

    My response: All the answers are incorrect.

    Your Response: The correct answer is: Create two new subnets in VPC A (172.16.0.0/28 and 172.16.0.16/29) Launch the E3 and E4 to these two subnets respectively with the appropriate custom private IP addresses. Create a new route table for VPC A, with unique route entries for the two EC2 servers in VPC B and VPC C.


    The Reasoning:

    Now the point I am trying to make in your solution you changed the destination server IP addresses in the diagram. There is a chance that you used the diagram as just a reference but In the question the server in VPC B and VPC C have the IP 10.0.0.10/32. but in the solution reference diagram the same ONE EC2 instance in each VPC has two different IP addresses 10.0.0.44/32 and 10.0.0.55/32. Now with two different IP address sure create one routing table and for each IP mark the destination as the appropriate the Peering connection and your work is done but going back to the original question if it was the same IP then you need two routing tables one per subnet and then create route entries for the either the entire subnet or just the server IP address 10.0.0.10/32 with destination as Peering connection.

    Also you source server IP addresses 172.16.0.88/32 and 172.16.0.99/32 are outside the proposed CIDR of the subnets in your solution. 172.16.0.0/28 ends at 172.16.0.15 and 172.16.0.16/28 will end at 0.31 which means both your IP addresses unfortunately are outside the range.

  • Carlo-TutorialsDojo

    Member
    November 25, 2022 at 1:09 am

    Hello JimmyD,

    Thanks for reaching out and giving us your feedback. I’ve already answered this question in another thread, so I’ll be copying my response. First, I acknowledge our mistake in the phrasing of the correct answer here. We can’t have two identical entries in a single RT, so there must be 2 RTs in the VPC A, each having an association with different subnets. Both RTs will contain destination routes to 10.0.0.0/16 with different peering targets.

    For example:

    VPC A -subnet1 RT:

    10.0.0.0/16 : pcx-aaabbb

    VPC A -subnet2 RT:

    10.0.0.0/16 : pcx-aaaccc

    I’ve already modified the item. The change should be reflected once our admin has reviewed it.

    For your second question, I’m not sure where you got the values 172.16.0.88/32 and 172.16.0.99/32. The source IPs that were mentioned in the scenario were 172.16.0.10 and 172.16.0.22.

    Let me know if there’s anything I can help you with.

    Regards,

    Carlo @ Tutorials Dojo

  • JimmyD

    Member
    November 27, 2022 at 1:10 am

    Thank you for you response. My apologies, I must have missed your first post.

    About the second question: I was referencing the IP addresses in the picture under the solution

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