Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company runs a web application on Amazon EC2 instances in an Auto Scaling group. The application experiences steady traffic during business hours and very low traffic overnight. The SysOps administrator wants to optimize costs by using a mix of On-Demand and Spot Instances. The administrator also requires that the total capacity never falls below the baseline level needed during business hours, even if Spot Instances are reclaimed. Which combination of Auto Scaling features should be used?
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
Best answer
Use a mixed instances policy and set the 'On-Demand Base' capacity to the minimum number of instances required during business hours, and 'On-Demand percentage above base' to 0% so that any additional capacity is Spot.
This ensures at least the baseline number of On-Demand instances always run, meeting the availability requirement. Any extra capacity uses Spot Instances for cost savings.
B
Distractor review
Use a launch template that specifies a Spot Instance type and set the total capacity to the desired level, relying on capacity rebalance to replace interrupted Spot Instances.
If all instances are Spot, the baseline capacity is not guaranteed because Spot Instances can be reclaimed at any time. Capacity rebalance helps but does not ensure capacity.
C
Distractor review
Purchase Compute Savings Plans to cover the entire Auto Scaling group, and use only Spot Instances for all capacity.
Savings Plans provide a discount but do not guarantee capacity. Spot Instances still risk interruption, so baseline capacity is not assured.
D
Distractor review
Configure the Auto Scaling group with a launch template that sets the instance market to 'spot' and use a scaling policy that always maintains the minimum capacity.
Even with a scaling policy, Spot Instances can be terminated by EC2, causing the group to fall below the minimum if replacements are delayed or unavailable.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
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?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Use a mixed instances policy and set the 'On-Demand Base' capacity to the minimum number of instances required during business hours, and 'On-Demand percentage above base' to 0% so that any additional capacity is Spot. — The question requires a baseline capacity that is always fulfilled even if Spot Instances are interrupted. An Auto Scaling group can define a mixed instances policy with weighted capacities, and a capacity rebalance is useful for proactive handling of Spot interruptions. However, to ensure baseline capacity, a launch template with On-Demand basis is not enough. The correct approach is to set a minimum number of On-Demand Instances that always run and supplement with Spot Instances for additional capacity. The 'On-Demand Base' capacity and 'On-Demand Percentage Above Base' in a mixed instances policy allow this. A simple launch template with Spot priority may not guarantee baseline. Capacity rebalance helps but does not enforce baseline.
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.
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