Question 732 of 1,705
Network ImplementationeasyMultiple ChoiceObjective-mapped

VPN Tunnel UP but No Connectivity? Fix Missing VPC Route to Virtual Private Gateway

This ANS-C01 practice question tests your understanding of network implementation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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 an AWS Site-to-Site VPN connection between their on-premises network and a VPC. The VPN tunnel status shows 'UP'. However, instances in the VPC cannot ping an on-premises server at 192.168.1.10. Which step should be taken to troubleshoot?

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

Verify that the VPC route table has a route to the on-premises network via the virtual private gateway

Option B is correct because even though the VPN tunnel is 'UP', traffic from the VPC to the on-premises network must be routed through the virtual private gateway (VGW). If the VPC route table does not contain a route for the on-premises CIDR (e.g., 192.168.1.0/24) pointing to the VGW, the instances have no path to reach the on-premises server, regardless of tunnel status.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

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

  • Verify that the internet gateway is attached to the VPC

    Why it's wrong here

    Internet gateway is not used for VPN traffic.

  • Verify that the VPC route table has a route to the on-premises network via the virtual private gateway

    Why this is correct

    Without this route, traffic from VPC to on-premises is dropped.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Verify that the security group for the instances allows outbound ICMP

    Why it's wrong here

    Security groups are stateful and allow outbound traffic by default.

  • Verify that the VPN tunnel is up on both ends

    Why it's wrong here

    The tunnel is already UP.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates see 'VPN tunnel status UP' and assume connectivity is fully functional, overlooking the critical requirement of a VPC route pointing to the virtual private gateway for traffic to traverse the tunnel.

Detailed technical explanation

How to think about this question

Under the hood, the VPC route table must have a static route for the on-premises CIDR (e.g., 192.168.1.0/24) with a target of the virtual private gateway (vgw-xxxx). Even if the VPN tunnel is established, the VPC's subnet router will drop packets destined for 192.168.1.10 if no such route exists. In real-world scenarios, this is often overlooked when the on-premises network uses a non-standard subnet or when route propagation from the VGW is not enabled or accepted.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

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

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.

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.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this ANS-C01 question test?

Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Verify that the VPC route table has a route to the on-premises network via the virtual private gateway — Option B is correct because even though the VPN tunnel is 'UP', traffic from the VPC to the on-premises network must be routed through the virtual private gateway (VGW). If the VPC route table does not contain a route for the on-premises CIDR (e.g., 192.168.1.0/24) pointing to the VGW, the instances have no path to reach the on-premises server, regardless of tunnel status.

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

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

1 more ways this is tested on ANS-C01

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A company has set up a site-to-site VPN connection between its on-premises network and AWS. The tunnel status shows 'UP' on both sides, but traffic from on-premises cannot reach EC2 instances in the VPC. What is the most likely cause?

medium
  • A.The pre-shared keys are mismatched.
  • B.The VPC route tables do not have a route pointing to the virtual private gateway for the on-premises CIDR.
  • C.The VPN tunnel has been idle for too long and needs to be re-initiated.
  • D.The security group associated with the EC2 instances does not allow inbound traffic from the VPN gateway.

Why B: Option B is correct because the most likely cause is that the VPC route tables lack a route pointing to the virtual private gateway (VGW) for the on-premises CIDR. Even though the VPN tunnel is UP (indicating Phase 1 and Phase 2 IPsec SAs are established), traffic from on-premises cannot reach EC2 instances if the VPC does not know how to forward return traffic back through the VGW. Without this route, the VPC drops inbound packets or sends them to the internet gateway instead of the VPN tunnel.

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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.