The answer is that the NAT gateway in VPC-B cannot provide internet access through a VPC peering connection because VPC peering does not support transitive routing. When the database in VPC-B attempts outbound updates, its traffic must traverse the peering link to VPC-A and then to the internet gateway, but peering connections explicitly forbid routing traffic from one peered VPC through another VPC’s internet gateway. This means the database’s default route (0.0.0.0/0) via the NAT gateway is unreachable for internet-bound traffic that must first cross the peering link. On the CompTIA Cloud+ CV0-004 exam, this scenario tests your understanding of VPC peering limitations and how they break common hybrid architectures like internet access via a peered NAT gateway. A frequent trap is assuming a NAT gateway in one VPC can serve as a proxy for resources in another peered VPC, but transitive routing is never allowed. Memory tip: “Peering is a direct bridge, not a relay—no hopping through another VPC’s gateway.”
CV0-004 Deployment Practice Question
This CV0-004 practice question tests your understanding of deployment. 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 financial services company is deploying a PCI-DSS compliant workload in a public cloud. The deployment must include a web application (port 443) and a database (port 3306). The security requirements mandate that the web application is internet-facing, but the database must be in a private subnet with no direct internet access. The cloud administrator creates two VPCs: one for the web tier and one for the database tier. The web tier is deployed in VPC-A with a public subnet and an internet gateway. The database tier is deployed in VPC-B with a private subnet and a NAT gateway for outbound updates. The administrator configures VPC peering between VPC-A and VPC-B, and updates route tables accordingly. The web application can connect to the database, but the database cannot initiate outbound connections to the internet for updates. What is the most likely issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The NAT gateway in VPC-B cannot be used for internet access through a VPC peering connection
The NAT gateway in VPC-B cannot be used for internet access through a VPC peering connection because VPC peering does not support transitive routing. When the database in VPC-B tries to reach the internet via the NAT gateway, traffic must go through the VPC peering connection to VPC-A and then to the internet gateway, but VPC peering does not allow a route that forwards traffic from one VPC to another VPC's internet gateway. The database's outbound traffic to the internet is effectively blocked because the NAT gateway's default route (0.0.0.0/0) points to the internet gateway in VPC-B, but the database's traffic must first traverse the peering connection, which is not a valid path for internet-bound traffic in this architecture.
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.
✗
The database security group does not allow outbound traffic to the internet
Why it's wrong here
Security groups are stateful; outbound is allowed by default.
✗
The route table in VPC-B does not have a default route to the NAT gateway
Why it's wrong here
The administrator says the route tables are updated, but the NATgateway may not work over peering.
✗
The VPC peering connection does not support DNS resolution between VPCs
Why it's wrong here
DNS resolution works across VPC peering if configured.
✓
The NAT gateway in VPC-B cannot be used for internet access through a VPC peering connection
Why this is correct
NAT gateways do not support traffic through VPC peering; each VPC needs its own NAT gateway.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a NATgateway in the same VPC as the database can provide internet access through a VPC peering connection, but they overlook the non-transitive nature of VPC peering, which prevents routing traffic from a peered VPC to an internet gateway or NAT gateway in the other VPC.
Detailed technical explanation
How to think about this question
VPC peering is a non-transitive, one-to-one connection that does not support edge-to-edge routing, meaning you cannot use a VPC peering connection to access resources like a NATgateway or internet gateway in a peered VPC. In AWS, to allow a private subnet in one VPC to access the internet through a NAT gateway in another VPC, you would need a transit gateway or a third-party virtual appliance, not a simple VPC peering connection. This limitation is explicitly documented in AWS VPC peering guides and is a common source of misconfiguration in multi-VPC architectures.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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.
Deployment — This question tests Deployment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The NAT gateway in VPC-B cannot be used for internet access through a VPC peering connection — The NAT gateway in VPC-B cannot be used for internet access through a VPC peering connection because VPC peering does not support transitive routing. When the database in VPC-B tries to reach the internet via the NAT gateway, traffic must go through the VPC peering connection to VPC-A and then to the internet gateway, but VPC peering does not allow a route that forwards traffic from one VPC to another VPC's internet gateway. The database's outbound traffic to the internet is effectively blocked because the NAT gateway's default route (0.0.0.0/0) points to the internet gateway in VPC-B, but the database's traffic must first traverse the peering connection, which is not a valid path for internet-bound traffic in this architecture.
What should I do if I get this CV0-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.