PAS-C01 Technology Practice Question
A company runs SAP on AWS and uses AWS Transit Gateway to connect multiple VPCs. They notice that inter-VPC traffic is being dropped. What is a likely cause?
⚠ Common exam trap
Watch out — candidates often assume Transit Gateway automatically enables inter-VPC routing without requiring explicit VPC route table entries, confusing Transit Gateway's transitive routing capability with the need for proper route propagation in each VPC.
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
✓
Missing routes in the VPC route tables pointing to the Transit Gateway.
AWS Transit Gateway requires explicit routes in each VPC's route table pointing to the Transit Gateway attachment ID for traffic to be forwarded between VPCs. Without these routes, the VPCs have no path to reach the Transit Gateway, causing inter-VPC traffic to be dropped at the VPC router level.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Security groups not allowing return traffic.
Why it's wrong here
Security groups are stateful.
- ✓
Missing routes in the VPC route tables pointing to the Transit Gateway.
Why this is correct
Without routes, traffic cannot be forwarded to Transit Gateway.
- ✗
Transit Gateway does not support transitive routing.
Why it's wrong here
Transit Gateway does support transitive routing.
- ✗
Network ACLs blocking traffic.
Why it's wrong here
NACLs could block, but missing routes is more likely.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PAS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PAS-C01 exam.