Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company has a VPC with a public subnet and a private subnet. An Amazon EC2 instance in the private subnet needs to download security patches from the internet, but the instance must not be directly accessible from the internet. The SysOps administrator configured a NAT gateway in the public subnet and added a route in the private subnet's route table pointing 0.0.0.0/0 to the NAT gateway. The instance's security group allows all outbound traffic. However, the instance still cannot reach the internet. What is the most likely missing configuration?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Attach an Elastic IP to the NAT gateway
An Elastic IP must be assigned when creating a NAT gateway. If it was created without one, it would have failed. Assuming the NAT gateway exists, an EIP is already attached.
B
Distractor review
Enable DNS resolution in the VPC
DNS resolution is not required for internet access via NAT gateway; it is used for resolving DNS names.
C
Best answer
Add a route in the public subnet's route table that directs 0.0.0.0/0 traffic to an internet gateway
The NAT gateway resides in the public subnet; that subnet's route table must have a route to an internet gateway for the NAT gateway to reach the internet.
D
Distractor review
Modify the network ACL of the private subnet to allow inbound ephemeral ports from the NAT gateway's private IP
By default, network ACLs allow all inbound/outbound traffic. If they have not been modified, they are not blocking traffic. This is rarely the cause.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Related practice questions
Related SOA-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A company uses Amazon CloudFront to deliver content to a global audience. The origin is an Application Load Balancer in us-east-1. The SysOps administrator wants to reduce costs by minimizing the number of requests that reach the origin server. Which action should the administrator take?
Question 2
A company runs a batch processing application on Amazon EC2 that runs for 2 hours every night. The workload can tolerate interruptions. Which EC2 purchasing option provides the lowest cost for this use case?
Question 3
A SysOps administrator needs to monitor the CPU utilization of an Amazon RDS DB instance and receive an alarm when CPU utilization exceeds 80% for 5 consecutive minutes. Which AWS service should be used to create this alarm?
Question 4
A company runs a critical web application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB). The application uses session stickiness (sticky sessions) to maintain user sessions. The SysOps administrator notices that when instances are replaced during a scale-in or failure event, users lose their session data. The administrator needs to preserve session data across instance failures without losing stickiness benefits. What should the administrator do?
Question 5
A company runs a production web application on a single Amazon EC2 instance. The application experiences a predictable and steady workload 24/7. The SysOps administrator wants to minimize compute costs for this instance while ensuring it remains available during the expected workload. Which EC2 purchasing option should the administrator use?
Question 6
A company has a VPC with public and private subnets. The private subnets host application servers that need to make outbound HTTPS connections to the internet. The SysOps administrator must implement a solution that provides outbound internet connectivity while preventing inbound connections from the internet. Additionally, the solution must allow the company to control which domains the application servers can access. Which solution should the administrator implement?
FAQ
Questions learners often ask
What does this SOA-C02 question test?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: Add a route in the public subnet's route table that directs 0.0.0.0/0 traffic to an internet gateway — For a NAT gateway to work, it must be placed in a public subnet that has a route to an internet gateway. The NAT gateway uses the internet gateway to send traffic to the internet. The most common oversight is that the public subnet's route table does not have a default route pointing to an internet gateway. Without this, the NAT gateway cannot forward traffic to the internet. While a NAT gateway requires an Elastic IP, it must be assigned during creation; the question states the NAT gateway was configured, so an EIP was likely attached. Network ACLs are default-allowed, so they are not typically the issue.
What should I do if I get this SOA-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
Loading comments…
Sign in to join the discussion.