Question 939 of 1,705
Network DesignhardMultiple ChoiceObjective-mapped

ANS-C01 Local route precedence Practice Question

This ANS-C01 practice question tests your understanding of network design. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: local route precedence. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A company has a VPC with multiple subnets and an AWS Transit Gateway. They have a requirement to inspect traffic between subnets using a third-party firewall appliance that is deployed in a centralized inspection VPC. The firewall appliance must process all traffic between the VPC subnets, including traffic between subnets in the same Availability Zone. Which routing configuration achieves this?

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

Create a VPC route table that routes the VPC CIDR to the Transit Gateway and associate it with each subnet.

None of the provided routing configurations can achieve this requirement because the local route for the VPC CIDR in any VPC route table cannot be overridden. Therefore, intra-VPC traffic will always use the local route and will not be sent to the Transit Gateway. To inspect traffic between subnets within the same VPC, alternative architectures such as a Gateway Load Balancer or a Transit Gateway with VPC peering between different VPCs must be used.

Key principle: Local route precedence

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Create a VPC route table that routes all traffic (0.0.0.0/0) to the Transit Gateway.

    Why it's wrong here

    Routes 0.0.0.0/0 to the Transit Gateway, which only affects internet-bound traffic, not intra-VPC traffic. Does not inspect inter-subnet traffic.

  • Create a VPC route table that routes the VPC CIDR to the Transit Gateway and associate it with each subnet.

    Why this is correct

    Attempts to route the VPC CIDR to the Transit Gateway, but the local route takes precedence, so traffic stays within the VPC. This does not achieve inspection.

    Related concept

    Local route precedence

  • Use the main route table and add a route for the VPC CIDR to the Transit Gateway.

    Why it's wrong here

    Same as B but uses the main route table. The local route still overrides, so intra-VPC traffic is not inspected.

  • Associate each subnet with a custom route table that has a route for the VPC CIDR to the Transit Gateway.

    Why it's wrong here

    Same as B and C but associates custom route tables with each subnet. The local route still overrides, so intra-VPC traffic remains local.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Candidates often assume that adding a route for the VPC CIDR to a Transit Gateway will override the implicit local route, but this is not possible. Intra-VPC traffic remains local.

Detailed technical explanation

How to think about this question

In AWS, each subnet has an implicit local route for the VPC CIDR that cannot be deleted or modified. To override this behavior, you must add a more specific route (e.g., the exact VPC CIDR) pointing to a Transit Gateway or virtual appliance; this route takes precedence over the local route because it is a static route with the same destination prefix. The Transit Gateway then uses its route tables to forward traffic to the inspection VPC, enabling centralized inspection of all east-west traffic, including traffic within the same Availability Zone.

KKey Concepts to Remember

  • Local route precedence

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Local route precedence

Real-world example

How this comes up in practice

A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

What to study next

Got this wrong? Here's your next step.

Review local route precedence, then practise related ANS-C01 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this ANS-C01 question test?

Network Design — This question tests Network Design — Local route precedence.

What is the correct answer to this question?

The correct answer is: Create a VPC route table that routes the VPC CIDR to the Transit Gateway and associate it with each subnet. — None of the provided routing configurations can achieve this requirement because the local route for the VPC CIDR in any VPC route table cannot be overridden. Therefore, intra-VPC traffic will always use the local route and will not be sent to the Transit Gateway. To inspect traffic between subnets within the same VPC, alternative architectures such as a Gateway Load Balancer or a Transit Gateway with VPC peering between different VPCs must be used.

What should I do if I get this ANS-C01 question wrong?

Review local route precedence, then practise related ANS-C01 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

Local route precedence

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Last reviewed: Jul 4, 2026

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This ANS-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 ANS-C01 exam.