← SOA-C02·Amazon Web Services

Question 190 of 1,546

Networking and Content Delivery →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is to enable DNS resolution for the VPC peering connection. This is correct because without DNS resolution enabled, DNS queries for public hostnames in the peered VPC return public IP addresses, forcing traffic to route over the internet or through NAT gateways instead of staying on the AWS global backbone. By enabling this setting, instances resolve those hostnames to private IPs, keeping traffic within AWS’s low-latency network and directly addressing the cross-region VPC peering high latency DNS resolution issue. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of how VPC peering DNS settings affect routing—a common trap is assuming ping success means optimal routing, but latency spikes often point to DNS misconfiguration. Remember the memory tip: “Peering without DNS is like dialing long-distance when you have a local line—always resolve to private IPs for the fastest path.”

SOA-C02 Networking and Content Delivery Practice Question

This SOA-C02 practice question tests your understanding of networking and content delivery. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 two VPCs in different AWS regions (us-east-1 and eu-west-1) that are peered. Applications in both VPCs need to communicate using private IP addresses. The ping tests are successful, but the latency is significantly higher than expected. Which change is most likely to improve the latency between the VPCs?

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.

Question 1hardmultiple choice

Full question →

A
Enable DNS resolution for the VPC peering connection.
Correct. When DNS resolution is enabled, instances can resolve private DNS names of instances in the peered VPC, ensuring traffic stays within the AWS backbone and avoids unnecessary hops or public internet routing.
B
Use a Transit Gateway instead of VPC Peering for cross-region connectivity.
Why wrong: Incorrect. Changing to Transit Gateway does not inherently improve latency; it adds a hub but traffic still traverses the AWS backbone.
C
Increase the MTU on the instances' network interfaces to 9001.
Why wrong: Incorrect. While jumbo frames can improve throughput, latency is not significantly affected by MTU changes.
D
Configure ECMP (Equal-Cost Multi-Path) routing on the VPC peering connection.
Why wrong: Incorrect. VPC Peering does not support ECMP; it is a one-to-one connection.

Full breakdown with real-world context →

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

✓

Enable DNS resolution for the VPC peering connection.

Option A is correct because enabling DNS resolution for the VPC peering connection allows instances to resolve public DNS hostnames to the private IP addresses of the peered VPC. Without this, DNS queries may return public IP addresses, forcing traffic to traverse the internet or NAT gateways, which adds significant latency. By resolving to private IPs, traffic stays within the AWS backbone, reducing latency.

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.

✓
Enable DNS resolution for the VPC peering connection.
Why this is correct
Correct. When DNS resolution is enabled, instances can resolve private DNS names of instances in the peered VPC, ensuring traffic stays within the AWS backbone and avoids unnecessary hops or public internet routing.
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.
✗
Use a Transit Gateway instead of VPC Peering for cross-region connectivity.
Why it's wrong here
Incorrect. Changing to Transit Gateway does not inherently improve latency; it adds a hub but traffic still traverses the AWS backbone.
✗
Increase the MTU on the instances' network interfaces to 9001.
Why it's wrong here
Incorrect. While jumbo frames can improve throughput, latency is not significantly affected by MTU changes.
✗
Configure ECMP (Equal-Cost Multi-Path) routing on the VPC peering connection.
Why it's wrong here
Incorrect. VPC Peering does not support ECMP; it is a one-to-one connection.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often assume latency is caused by network path or bandwidth issues (leading them to choose Transit Gateway or MTU changes), but the real culprit is DNS resolution misconfiguration forcing traffic over the public internet instead of the private AWS backbone.

Detailed technical explanation

How to think about this question

When DNS resolution is not enabled for a VPC peering connection, the default behavior for public DNS hostnames (e.g., ec2-xxx.compute-1.amazonaws.com) is to resolve to the public IP of the instance. This forces traffic to egress through an internet gateway, traverse the public internet, and then ingress through the destination VPC's internet gateway, adding significant latency and potential packet loss. Enabling DNS resolution (via the RequesterDNSResolution attribute) ensures that DNS queries return the private IP of the peered instance, keeping traffic on the AWS global network, which is optimized for low latency and high throughput.

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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.

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 SOA-C02 question test?

Networking and Content Delivery — This question tests Networking and Content Delivery — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Enable DNS resolution for the VPC peering connection. — Option A is correct because enabling DNS resolution for the VPC peering connection allows instances to resolve public DNS hostnames to the private IP addresses of the peered VPC. Without this, DNS queries may return public IP addresses, forcing traffic to traverse the internet or NAT gateways, which adds significant latency. By resolving to private IPs, traffic stays within the AWS backbone, reducing latency.

What should I do if I get this SOA-C02 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.

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This SOA-C02 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 SOA-C02 exam.