SOA-C02 Cost and Performance Optimization — 30 Questions

Question 1

A company uses Amazon S3 to store large files that are frequently accessed for the first 30 days after upload. After 30 days, access frequency drops significantly but users still need retrieval within minutes. The SysOps administrator wants to minimize storage costs while ensuring low-latency access for frequently accessed files and automatic optimization for changing access patterns. Which S3 storage class configuration should the company use?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Use S3 Intelligent-Tiering. B is correct because S3 Intelligent-Tiering automatically moves objects between access tiers (frequent and infrequent access, with optional archive access tiers) based on changing access patterns, with no retrieval fees for the frequent and infrequent access tiers and low-latency access. This matches the requirement of frequent access for the first 30 days, then infrequent access with minutes-later retrieval, while minimizing storage costs without manual intervention.

Answer

Use S3 Standard for all objects, and manually move older objects to S3 Standard-IA after 30 days.

Answer

Use S3 Standard-IA for all objects, and accept higher retrieval costs for the first 30 days.

Answer

Use S3 Glacier Instant Retrieval

Question 2

A company runs a mix of Amazon EC2 instances, Amazon RDS databases, and AWS Lambda functions for production workloads. The workloads are steady-state and predictable. The SysOps administrator wants to reduce costs while maintaining flexibility to change instance families and regions. Which pricing model should be recommended?

Accepted Answer

Standard Reserved Instances. Standard Reserved Instances provide significant discounts for steady-state, predictable workloads on both EC2 and RDS. Although they lock you into a specific instance family and region, you can choose Convertible Reserved Instances to retain some flexibility. Compute Savings Plans do not cover RDS databases, which are explicitly part of the workload mix, making them unsuitable. Spot Instances are not designed for steady-state workloads, and EC2 Instance Savings Plans only cover EC2 instances.

Answer

EC2 Instance Savings Plans

Answer

Compute Savings Plans

Answer

Spot Instances

Question 3

A company stores video files in Amazon S3. Files are accessed frequently for the first 30 days, then weekly for the next 6 months, and then rarely after that. Files must be retained for 5 years and any access must be served within minutes. The SysOps administrator wants to minimize storage costs. Which lifecycle policy is most cost-effective?

Accepted Answer

Transition to S3 Standard-Infrequent Access after 30 days, then to S3 Glacier Instant Retrieval after 6 months.. Transition objects to S3 Standard-IA after 30 days to match the weekly access pattern at lower cost than S3 Standard. Then transition to S3 Glacier Instant Retrieval after 6 months for data that is rarely accessed but requires retrieval within milliseconds. Glacier Instant Retrieval offers the lowest storage cost among storage classes that support millisecond retrieval, making it ideal for long-term retention with the requirement that any access be served within minutes. Other classes like Glacier Deep Archive do not support expedited retrieval and have retrieval times of 12–48 hours, which fails to meet the within-minutes requirement.

Answer

Transition to S3 Standard-Infrequent Access after 30 days, then to S3 Glacier Deep Archive after 6 months.

Answer

Transition to S3 One Zone-Infrequent Access after 30 days, then to S3 Glacier after 6 months.

Answer

Transition to S3 Intelligent-Tiering after 30 days, then to S3 Glacier Flexible Retrieval after 6 months.

Question 4

A company runs a CPU-intensive batch processing job daily on a single Amazon EC2 instance. The job requires high compute performance but uses minimal memory. The instance is typically idle for the rest of the day. The SysOps administrator needs to minimize costs while ensuring the job completes within a 1-hour window. Which purchasing option and instance family should the administrator use?

Accepted Answer

Reserved Instance (1-year, all upfront) with a compute-optimized (C-family) instance. A Reserved Instance with a compute-optimized (C-family) instance is the appropriate choice because the job requires high CPU performance and must complete reliably within a 1-hour window. Spot Instances are subject to interruption and cannot guarantee completion, especially for a single-instance batch job. While Reserved Instances involve a 1-year commitment, this option ensures the instance is available when needed, and the compute-optimized family matches the CPU-intensive profile. On-Demand instances would be cheaper for low utilization, but that option is not available with a compute-optimized family in the given choices.

Answer

On-Demand Instance with a general-purpose (T-family) instance

Answer

Spot Instance with a compute-optimized (C-family) instance

Answer

On-Demand Instance with a memory-optimized (R-family) instance

Question 5

A company runs a batch processing job every night that takes exactly 2 hours to complete. The job is time-sensitive and cannot tolerate interruptions. The SysOps administrator needs to minimize compute costs for the Amazon EC2 instances used during this job. The job runs every day and has predictable resource requirements. Which purchasing option should the administrator choose?

Accepted Answer

Reserved Instances (Standard). A Standard Reserved Instance is the best choice because the job runs every night for exactly 2 hours with predictable resource requirements, making it ideal for a 1-year or 3-year commitment that provides a significant discount (up to 72%) over On-Demand pricing. Since the job cannot tolerate interruptions, Reserved Instances offer capacity reservation and cost savings without the risk of termination that Spot Instances carry.

Answer

Spot Instances

Answer

On-Demand Instances

Answer

Dedicated Hosts

Question 6

A company runs a web application on a fleet of Amazon EC2 instances. The application uses Amazon EBS volumes of type gp2 (General Purpose SSD). Each volume is 100 GB, which provides a baseline of 3000 IOPS (the minimum performance of gp2). The SysOps administrator monitors the volumes and finds that the average IOPS used is only 1,500, and the application performance is adequate. The administrator wants to reduce storage costs without affecting performance. Which action should the administrator take?

Accepted Answer

Migrate the volumes from gp2 to gp3 and provision the baseline IOPS to match the actual usage.. Migrating from gp2 to gp3 is the correct action because gp3 has a lower per-GB cost while providing a baseline of 3,000 IOPS and 125 MB/s. For a 100 GB gp2 volume, the baseline is only 300 IOPS (3 IOPS/GB), so the observed usage of 1,500 IOPS would actually exceed that baseline and rely on burst credits. Migrating to gp3 guarantees a 3,000 IOPS baseline, which removes the need for burst credits and reduces cost. Note that gp3 IOPS cannot be set below 3,000; the cost benefit comes from the lower per-GB price, not from provisioning lower IOPS.

Answer

Replace the EBS volumes with instance store volumes.

Answer

Change the volume type to io2 (Provisioned IOPS SSD) and reduce the provisioned IOPS.

Answer

Change the volume type to Cold HDD (sc1) to reduce cost.

Question 7

A SysOps administrator notices that some Amazon S3 objects have not been accessed for over 90 days and need to be retained for compliance purposes. The administrator wants to reduce storage costs by moving these objects to the lowest-cost storage class. Which action should the administrator take?

Accepted Answer

Create an S3 lifecycle rule to transition objects older than 90 days to S3 Glacier Deep Archive.. S3 Glacier Deep Archive is the lowest-cost storage class in Amazon S3, designed for long-term retention of data that is accessed infrequently. An S3 lifecycle rule can automatically transition objects older than 90 days to this class, reducing costs without manual intervention. This meets the compliance requirement to retain the objects while optimizing storage expenditure.

Answer

Manually move the objects to S3 One Zone-IA.

Answer

Use S3 Intelligent-Tiering.

Answer

Enable S3 Versioning and create a lifecycle rule to delete old versions.

Question 8

Match each AWS security service to its purpose.

Accepted Answer

AWS WAF: A web application firewall that helps protect web applications from common web exploits. These services are core to AWS security. AWS WAF protects web applications from exploits, AWS Shield protects against DDoS attacks, AWS IAM manages user access and permissions, and AWS KMS manages encryption keys. Common confusions include mixing WAF and Shield (both are protective but for different threats) and IAM with KMS (IAM for access, KMS for encryption).

Answer

AWS WAF: A managed Distributed Denial of Service (DDoS) protection service that safeguards applications running on AWS

Answer

AWS IAM: A managed service that makes it easy to create and control the encryption keys used to encrypt your data

Question 9

A company is using Amazon S3 to store historical data. The data is accessed frequently for the first 30 days, then accessed infrequently for the next 90 days, and after 120 days it is rarely accessed but must be retained for 7 years for compliance. Which S3 lifecycle policy provides the LOWEST cost while meeting these requirements?

Accepted Answer

Standard for 30 days, then transition to Standard-IA for 90 days, then to Glacier Deep Archive.. It aligns the storage class transitions precisely with the access patterns: Standard for frequent access (first 30 days), Standard-IA for infrequent access (next 90 days), and Glacier Deep Archive for long-term retention (after 120 days). This minimizes cost by avoiding paying for premium storage when data is rarely accessed, while still meeting the 7-year compliance requirement at the lowest possible storage cost.

Answer

Standard for 30 days, then transition to One Zone-IA for 90 days, then to Glacier Deep Archive.

Answer

Standard for 120 days, then transition to Glacier Deep Archive.

Answer

Standard for 30 days, then transition to Glacier for the remaining life.

Question 10

Which TWO actions can reduce costs for an Amazon EC2 environment that runs non-critical batch jobs that can be interrupted? (Choose TWO.)

Accepted Answer

Use Scheduled Reserved Instances.. Option A (Use Scheduled Reserved Instances) is correct because Scheduled Reserved Instances let you reserve capacity for a recurring schedule (e.g., specific hours/days), which matches predictable batch windows and is cheaper than On-Demand for that committed usage. Option D (Use Spot Instances for the batch jobs) is correct because Spot Instances offer up to ~90% discounts off On-Demand and are ideal for interruptible, non-critical workloads since AWS can reclaim them with a 2-minute interruption notice. Option B (Elastic IP addresses) is incorrect because Elastic IPs are for static public IPv4 addressing and do not reduce compute costs (and unattached EIPs can incur charges). Option C (Dedicated Hosts) is incorrect because Dedicated Hosts are for licensing/compliance and physical server isolation, typically costing more, not less. Option E (On-Demand Instances) is incorrect because On-Demand is the most expensive flexible option and provides no cost savings for interruptible batch jobs.

Answer

Associate Elastic IP addresses with the instances.

Answer

Use Dedicated Hosts.

Answer

Use On-Demand Instances.

Question 11

A company is running a web application on EC2 instances behind an Application Load Balancer. The application experiences variable traffic patterns. The SysOps team wants to optimize costs without impacting performance. Which EC2 purchasing option should the team use for the instances?

Accepted Answer

Savings Plans. Savings Plans offer flexible pricing across EC2 instance families and regions, providing significant discounts (up to 72%) compared to On-Demand. With variable traffic, they allow cost savings without requiring a specific instance configuration or long-term commitment to a particular instance type. The plan applies to any EC2 usage, making it ideal for workloads with unpredictable or changing patterns, while performance remains unaffected since instances still run as On-Demand.

Answer

Spot Instances

Answer

On-Demand Instances

Answer

Reserved Instances

Question 12

A company uses S3 Standard for all data, but some objects are accessed only once per year. Which storage class provides the lowest cost for this use case while maintaining the same durability?

Accepted Answer

S3 Glacier Deep Archive. S3 Glacier Deep Archive provides the lowest storage cost for data accessed once per year, with the same 99.999999999% (11 nines) durability as S3 Standard, because it is designed for long-term retention with retrieval times of 12 hours or more. The infrequent access pattern makes the lower retrieval costs of Glacier Deep Archive more economical than any other S3 storage class.

Answer

S3 One Zone-Infrequent Access (S3 One Zone-IA)

Answer

S3 Intelligent-Tiering

Answer

S3 Standard-Infrequent Access (S3 Standard-IA)

Question 13

A SysOps administrator is designing a cost-effective architecture for a batch processing workload that runs once per day and can tolerate interruptions. The workload uses EC2 instances. Which TWO purchasing options should the administrator consider? (Choose two.)

Accepted Answer

Spot Instances. Spot Instances (B) are correct because the workload is batch processing that can tolerate interruptions, so bidding on spare EC2 capacity provides the deepest discounts (up to 90% off On-Demand) and instances can be reclaimed with a two-minute warning. On-Demand Instances (C) are correct because they provide interruption-free capacity billed per second with no upfront commitment, making them a cost-effective fallback for the daily batch run when Spot capacity is unavailable or when the job must complete reliably. Dedicated Hosts (A) are not appropriate because they are the most expensive option, designed for licensing and compliance requirements, not cost-effective interruptible batch work. Reserved Instances (D) do not fit because a 1- or 3-year commitment is wasteful for a workload that only needs capacity once per day and can be interrupted. Capacity Reservations (E) guarantee capacity in a specific AZ but carry On-Demand-like pricing with no discount, so they add cost without benefit for an interruption-tolerant batch job.

Answer

Dedicated Hosts

Answer

Reserved Instances (Standard)

Answer

Capacity Reservations

Question 14

A company runs a production web application on Amazon EC2 instances behind an Application Load Balancer. The application experiences variable traffic patterns, with peak usage during business hours. The company wants to optimize costs while maintaining performance. What should the SysOps administrator do?

Accepted Answer

Use a combination of On-Demand and Spot Instances, with On-Demand for baseline traffic and Spot for burst capacity.. Using a combination of On-Demand and Spot Instances optimizes costs: On-Demand covers baseline traffic reliably, while Spot Instances provide cheap burst capacity for peak loads. This matches the variable traffic pattern and maintains performance during peaks, assuming the application can handle Spot interruptions.

Answer

Increase the EC2 instance sizes to handle peak load at all times.

Answer

Purchase Reserved Instances for all instances to get the lowest hourly rate.

Answer

Use Dedicated Hosts to ensure consistent performance.

Question 15

A company has a production RDS for PostgreSQL database with a db.r5.large instance. The database experiences high read traffic during business hours. The SysOps administrator needs to improve read performance and ensure high availability at minimal cost. Which solution should the administrator implement?

Accepted Answer

Create a Multi-AZ deployment and then add a Read Replica in a different Availability Zone.. Creating a Multi-AZ deployment provides high availability with automatic failover, and adding a Read Replica in a different AZ offloads read traffic, improving read performance. This combination addresses both requirements at minimal cost compared to scaling up the instance. Read Replicas can also be promoted to primary if needed.

Answer

Upgrade the instance to db.r5.xlarge and enable automatic backups.

Answer

Enable Multi-AZ on the existing instance to provide automatic failover but no read scaling.

Answer

Use Amazon ElastiCache for Redis to cache frequent queries.

Question 16

A company uses Amazon S3 to store backups and logs. The total data volume is 50 TB and grows by 2 TB per month. The company requires that data be retained for 7 years. Which THREE actions will optimize storage costs? (Choose THREE.)

Accepted Answer

Use S3 Lifecycle policies to transition data to S3 Glacier Deep Archive after 30 days.. The correct answers are A, B, and D. S3 Lifecycle policies help optimize storage costs. Option A transitions data to S3 Glacier Deep Archive, the lowest-cost storage class for long-term retention. Option B expires incomplete multipart uploads, preventing unnecessary storage charges. Option D uses S3 Intelligent-Tiering, which automatically moves data between tiers based on changing access patterns, reducing costs for infrequently accessed data with unknown patterns. Option C is incorrect because deleting data after one year fails to meet the 7-year retention requirement. Option E is incorrect because S3 Glacier Flexible Retrieval is more expensive than S3 Glacier Deep Archive and is not necessary for data that is rarely accessed.

Answer

Store all data in S3 Standard for the first year, then delete.

Answer

Use S3 Glacier Flexible Retrieval to allow data retrieval in minutes.

Question 17

A SysOps administrator attached the IAM policy shown to a user. The user needs to launch EC2 instances for a cost-sensitive project. What is the impact of this policy on cost optimization?

Accepted Answer

The policy allows launching any number of t3.micro instances, potentially increasing costs if many instances are launched.. The policy allows launching any number of t3.micro instances because it does not include any conditions that limit the number or total cost. While t3.micro instances are relatively cheap, launching many of them can still increase costs significantly. Therefore, the policy does not enforce cost optimization beyond restricting instance type.

Answer

The policy is too restrictive because it only allows t3.micro instances, which may not be sufficient for production workloads.

Answer

The policy does not allow launching any instances because the condition is on RunInstances.

Answer

The policy ensures cost control by allowing only t3.micro instances, which are the cheapest.

Question 18

A SysOps administrator reviews the Lambda invocation metrics for a function. The function processes data from an S3 bucket and is triggered by S3 events. The cost for this function is higher than expected. What should the administrator do to reduce costs?

Accepted Answer

Increase the function's memory allocation to reduce execution time.. Lambda pricing is based on GB-seconds (memory × duration) plus invocation count. Increasing memory allocation gives the function more CPU proportionally, which can dramatically reduce execution time. If the function is CPU-bound, the total GB-seconds can decrease even though the per-millisecond rate is higher, lowering overall cost.

Answer

Set a reserved concurrency limit to cap the number of concurrent executions.

Answer

Change the function to be invoked on a schedule instead of by S3 events.

Answer

Reduce the function's memory allocation to lower cost per invocation.

Question 19

A company has a production RDS MySQL instance with 500 GB of gp2 storage. The database experiences high read traffic. The SysOps team needs to improve read performance at minimal cost. What should they do?

Accepted Answer

Create one or more RDS Read Replicas in the same region and direct read traffic to them.. Creating RDS Read Replicas in the same region offloads read queries from the primary instance, improving read performance cost-effectively. Horizontal scaling with replicas is typically cheaper and more scalable than vertical scaling. Option A is wrong: migrating to Aurora is more expensive and auto scaling is not the primary solution for read-heavy workloads. Option B is wrong: switching to gp3 and increasing IOPS improves storage performance, but the bottleneck is more likely database processing, not IOPS. Option C is wrong: upgrading to a larger instance type increases cost without the scalability of replicas and may require downtime.

Answer

Migrate the database to Amazon Aurora with Auto Scaling enabled.

Answer

Change the storage type to gp3 and increase IOPS.

Answer

Upgrade the DB instance to a larger instance type with more vCPUs.

Question 20

A SysOps administrator is investigating a cost increase in a production AWS account. They notice that an EC2 instance with a Reservation has been running continuously for months. The instance type is m5.large in us-east-1. The administrator sees that the instance is using a Standard Reserved Instance (RI) that was purchased 6 months ago for a 1-year term. However, the current utilization shows that the instance is only used for 4 hours per day. What should the administrator do to optimize costs without affecting availability?

Accepted Answer

Modify the existing RI to a smaller instance size (e.g., m5.large to m5.xlarge? no, smaller: e.g., t3.medium) and use Auto Scaling with a schedule to start/stop the instance during business hours.. By modifying the existing Standard RI to a smaller instance size (e.g., within the same family or by converting to a Convertible RI to allow family changes), the administrator can better match the actual low utilization pattern. Additionally, using Auto Scaling with a scheduled scaling policy to start and stop the instance during business hours ensures availability during needed times and reduces waste. Option A is incorrect because stopping the instance does not stop the RI charges; Reserved Instance benefits are applied only to running instances, so the RI would be wasted during off-hours. Option B is incorrect because selling the RI on the Reserved Instance Marketplace typically incurs a loss of the upfront payment and does not directly address the over-provisioning issue. Option D is incorrect because converting to a larger instance family would increase compute capacity per hour, leading to higher costs and even more waste given the low utilization.

Answer

Stop the instance during off-hours using Instance Scheduler, but keep the RI as-is.

Answer

Sell the current RI on the Reserved Instance Marketplace and purchase a new Convertible RI for a smaller instance type.

Answer

Convert the RI to a Convertible RI and exchange it for a larger instance family to get more compute per hour.