ANS-C01 Network Implementation Practice Question
A company has a VPC with an IPv4 CIDR block of 10.0.0.0/16. They need to connect two separate branch offices using AWS Client VPN. Each branch office has a different subnet: Branch A uses 10.0.1.0/24 and Branch B uses 10.0.2.0/24. The Client VPN endpoint is configured with a CIDR range of 10.0.3.0/24. The route table for the VPC has the local route and routes to the Client VPN endpoint. Users from both branches can connect to the VPN but cannot communicate with each other. What is the most likely reason?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The branch subnets 10.0.1.0/24 and 10.0.2.0/24 are part of the VPC CIDR, so the VPC routes traffic locally instead of via the VPN
Branch subnets overlap with the VPC CIDR, causing routing conflicts. The VPC sees 10.0.1.0/24 and 10.0.2.0/24 as local, thus traffic destined to those addresses is routed locally within the VPC, not to the VPN. Options B and C are not relevant to inter-branch communication. Option D would not cause the issue because branch subnets are within the VPC CIDR.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The branch subnets 10.0.1.0/24 and 10.0.2.0/24 are part of the VPC CIDR, so the VPC routes traffic locally instead of via the VPN
Why this is correct
Local routes take precedence.
- ✗
The route tables in the branch subnets do not have routes to the Client VPN endpoint
Why it's wrong here
Branches can connect to VPN, so routes exist.
- ✗
The Client VPN endpoint is configured with a CIDR that overlaps with the branch subnets
Why it's wrong here
Client VPN CIDR is 10.0.3.0/24, not overlapping.
- ✗
The security group for the Client VPN endpoint does not allow inbound traffic from branch subnets
Why it's wrong here
Security group would affect all traffic, not just inter-branch.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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