SOA-C02 Reliability and Business Continuity Practice Test 8 — 15 Questions

Question 1

A company runs a web application on EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application stores session data in an in-memory cache on the EC2 instances. During an instance refresh, users lose their session data. Which action should be taken to improve reliability without major application changes?

Accepted Answer

Move session state to Amazon ElastiCache for Redis.. Option B is correct because ElastiCache provides a managed, external caching layer that preserves session data independently of EC2 instance lifecycle. Option A is incorrect because sticky sessions (session affinity) still lose data when instances are terminated. Option C is incorrect because ElastiCache for Redis is more appropriate than Memcached for session persistence with replication. Option D is incorrect because increasing instance count does not address session data loss.

Answer

Use ElastiCache for Memcached with auto-discovery.

Answer

Increase the minimum size of the Auto Scaling group.

Answer

Enable sticky sessions (session affinity) on the ALB target group.

Question 2

A company runs a production RDS for PostgreSQL instance with Multi-AZ enabled. The database experiences a failover due to an AZ outage. After the failover, the application experiences high latency on write operations. What is the most likely cause?

Accepted Answer

Synchronous replication to the standby instance in the other AZ is causing additional latency.. Option A is correct because synchronous replication in Multi-AZ requires acknowledgment from the standby before the transaction is committed, increasing write latency. Option B is incorrect because the standby is in a different AZ and is not used for reads automatically. Option C is incorrect because synchronous replication does not use asynchronous replication. Option D is incorrect because the Multi-AZ feature does not use a read replica; it uses a standby in a different AZ.

Answer

The application is now reading from the standby instance, which has higher read latency.

Answer

The failover switched to a read replica in a different AZ.

Answer

The failover switched to asynchronous replication mode.

Question 3

A SysOps administrator is designing a disaster recovery plan for a critical application that runs on EC2 instances with data stored on EBS volumes. The application requires an RPO of 15 minutes and an RTO of 2 hours. The current solution uses EBS snapshots taken every 6 hours. The administrator needs to improve the backup strategy to meet the RPO. What is the most cost-effective way to achieve this?

Accepted Answer

Increase the snapshot frequency to every 15 minutes.. Option D is correct because increased snapshot frequency (e.g., every 15 minutes) directly reduces RPO. Option A is incorrect because Recycle Bin only prevents accidental deletion, it does not create new snapshots. Option B is incorrect because changing volume type does not affect snapshot frequency. Option C is incorrect because EBS Multi-Attach does not provide snapshot capabilities.

Answer

Enable EBS Recycle Bin with a retention rule of 15 minutes.

Answer

Change the EBS volume type to io2 Block Express.

Answer

Use EBS Multi-Attach to attach volumes to multiple instances for redundancy.

Question 4

A company runs a stateless web application on EC2 instances in an Auto Scaling group. The instances are behind an Application Load Balancer. The Auto Scaling group uses a dynamic scaling policy based on average CPU utilization. During a traffic spike, new instances are launched but take 5 minutes to become healthy. Users experience errors during this time. Which solution would reduce the time to serve traffic from new instances?

Accepted Answer

Use a launch template with a pre-provisioned AMI.. Option C is correct because a launch template with a pre-warmed AMI avoids the initialization steps during scale-out. Option A is incorrect because increasing the cooldown period delays scaling, making the problem worse. Option B is incorrect because instance type does not affect startup time significantly. Option D is incorrect because lifecycle hooks add delay, not reduce it.

Answer

Add a lifecycle hook to delay instance termination.

Answer

Increase the cooldown period for the scaling policy.

Answer

Use a larger instance type.

Question 5

An organization is using AWS CloudFormation to deploy infrastructure. The SysOps administrator needs to ensure that if a stack update fails, the stack automatically rolls back to the last known good state. Which stack update option should be configured?

Accepted Answer

Rollback on failure. Option A is correct because the Rollback on failure setting causes CloudFormation to automatically revert to the previous state if the update fails. Option B is incorrect because Disable rollback is the opposite. Option C is incorrect because Stack policy controls updates to specific resources, not rollback behavior. Option D is incorrect because Change sets allow preview of changes but do not control automatic rollback.

Answer

Disable rollback

Answer

Change sets

Answer

Stack policy

Question 6

A company runs a critical database on an EC2 instance with an EBS volume. The administrator wants to create a disaster recovery plan that can recover the database in a different AWS Region within 4 hours. The database size is 1 TB. What is the MOST efficient approach to meet the RTO?

Accepted Answer

Copy the AMI and underlying EBS snapshots to the DR region.. Option D is correct because copying the AMI and snapshot to another region allows launching an instance there. Option A is incorrect because sharing does not copy to another region. Option B is incorrect because EBS snapshots are regional, not global. Option C is incorrect because AWS Backup can copy to another region, but the process is similar to manual copy; however, the key is to have the AMI/snapshot available in the DR region.

Answer

Share the AMI with the target region.

Answer

Use EBS snapshots directly in the DR region.

Answer

Configure AWS Backup to copy backups to the DR region.

Question 7

A company uses AWS CloudTrail to log API activity. The SysOps administrator needs to ensure that log files are protected from accidental deletion and are available for compliance audits for at least 7 years. Which service should be used to meet these requirements?

Accepted Answer

Enable S3 Object Lock in Compliance mode.. Option B is correct because S3 Object Lock with Compliance mode prevents deletion and ensures immutability. Option A is incorrect because versioning alone does not prevent deletion. Option C is incorrect because Glacier has retrieval delays and no write-once-read-many (WORM) protection. Option D is incorrect because CloudWatch Logs can store logs but does not provide WORM protection natively.

Answer

Enable S3 Versioning on the CloudTrail S3 bucket.

Answer

Move CloudTrail logs to Amazon S3 Glacier after 90 days.

Answer

Store logs in Amazon CloudWatch Logs with an expiration policy of 7 years.

Question 8

An application running on Amazon ECS with Fargate launch type is experiencing intermittent failures. The tasks are spread across multiple Availability Zones. The SysOps administrator notices that failures occur only when an entire AZ becomes unavailable. What should the administrator do to improve the reliability of the application?

Accepted Answer

Increase the desired task count to ensure sufficient capacity across AZs.. Option A is correct because increasing the number of tasks ensures that even if one AZ fails, tasks in other AZs can handle the load. Option B is incorrect because using more subnets does not necessarily improve availability. Option C is incorrect because placement groups are not applicable to Fargate. Option D is incorrect because EFS is for shared storage, not compute reliability.

Answer

Use multiple subnets in the same AZ.

Answer

Use a cluster placement group.

Answer

Attach an Amazon EFS filesystem to all tasks.

Question 9

A company uses Amazon Route 53 for DNS and has a domain registered with Route 53. The company wants to ensure that if the primary web server fails, traffic is automatically routed to a secondary server in a different region. The health check must consider both the server response and the application response time. Which routing policy should be used?

Accepted Answer

Failover routing policy. Option C is correct because failover routing with health checks directs traffic to the primary if healthy, otherwise to the secondary. Option A is incorrect because latency routing does not provide automatic failover based on health. Option B is incorrect because weighted routing distributes traffic regardless of health. Option D is incorrect because geolocation routing is based on the user's location, not health.

Answer

Weighted routing policy

Answer

Geolocation routing policy

Answer

Latency routing policy

Question 10

Which TWO actions should a SysOps administrator take to ensure high availability of a web application running on EC2 instances? (Choose two.)

Accepted Answer

Configure an Auto Scaling group with a health check to replace unhealthy instances.. Options B and D are correct. Deploying across multiple Availability Zones ensures that an AZ failure does not take down the entire application. Using an Auto Scaling group with a health check automatically replaces unhealthy instances. Option A is incorrect because a single AZ is a single point of failure. Option C is incorrect because a larger instance type does not provide high availability. Option E is incorrect because termination protection does not automatically replace instances; it only prevents accidental termination.

Answer

Enable termination protection on all EC2 instances.

Answer

Launch all EC2 instances in a single Availability Zone.

Answer

Use a larger instance type for all EC2 instances.

Question 11

Which THREE measures can be used to improve the recovery time objective (RTO) for a database running on Amazon RDS? (Choose three.)

Accepted Answer

Use a read replica and promote it during a failure.. Options A, B, and D are correct. Multi-AZ provides automatic failover, reducing RTO. Automated backups with point-in-time recovery allow quick restore to a specific time. Read replicas can be promoted to primary quickly. Option C is incorrect because manual snapshots require manual restore, which is slower. Option E is incorrect because deletion protection is about preventing deletion, not recovery.

Answer

Enable deletion protection.

Answer

Create manual snapshots daily.

Question 12

Which TWO steps should a SysOps administrator take to ensure data durability for an Amazon S3 bucket that stores critical documents? (Choose two.)

Accepted Answer

Enable S3 Versioning.. Options B and C are correct. S3 Versioning protects against accidental overwrites and deletions. Cross-region replication ensures data survives a regional disaster. Option A is incorrect because SSE-S3 provides encryption at rest, not durability. Option D is incorrect because MFA Delete adds security but does not directly improve durability. Option E is incorrect because transfer acceleration improves upload speed, not durability.

Answer

Enable default encryption with SSE-S3.

Answer

Use S3 Transfer Acceleration.

Answer

Enable MFA Delete.

Question 13

A company runs a web application on EC2 instances behind an Application Load Balancer. The database is an RDS MySQL instance with Multi-AZ enabled. The application experiences intermittent 5xx errors that correlate with database failover events. What is the MOST likely cause and solution?

Accepted Answer

Enable DNS caching with a low TTL in the application and use the RDS instance endpoint with a retry mechanism.. Option D is correct because during a database failover, the DNS record for the RDS endpoint changes, and if the application caches the DNS resolution, it may try to connect to the old primary. Enabling TTL-aware caching forces the application to re-resolve DNS quickly. Option A is wrong because Multi-AZ already provides a standby; using a read replica does not address write failures. Option B is wrong because the issue is DNS caching, not missing read replicas. Option C is wrong because increasing connection pool size does not handle DNS changes.

Answer

Configure the application to use the RDS reader endpoint.

Answer

Use a read replica to offload read traffic and reduce failover impact.

Answer

Increase the database connection pool size to handle retries.

Question 14

A company uses AWS Backup to back up its Amazon EFS file system daily. The backup retention policy is set to 30 days. Recently, a user accidentally deleted a critical directory. The company wants to restore the directory as it existed 2 days ago. What is the MOST cost-effective and quickest way to achieve this?

Accepted Answer

Restore the backup from 2 days ago to a new EFS file system, then copy the directory to the original file system.. Option B is correct because AWS Backup creates recovery points that can be restored to a new EFS file system, and then the specific directory can be copied. Option A is wrong because EFS does not have a native trash feature. Option C is wrong because enabling EFS replication is not a backup replacement and does not provide point-in-time recovery. Option D is wrong because restoring to an on-premises server is unnecessary and slower.

Answer

Use the EFS console to recover the directory from the .Trash folder.

Answer

Enable EFS replication to another region and then fail back.

Answer

Use AWS Backup to restore the entire file system to an on-premises server, then copy the directory back.

Question 15

A SysOps administrator needs to ensure that an Amazon S3 bucket can withstand the loss of an entire AWS Availability Zone. What is the SIMPLEST configuration to meet this requirement?

Accepted Answer

Use S3 Standard storage class.. Option C is correct because S3 Standard is designed for 99.99% availability and can withstand the loss of two facilities concurrently. Option A is wrong because cross-region replication is for disaster recovery, not just AZ resilience. Option B is wrong because S3 One Zone-IA does not survive AZ loss. Option D is wrong because MFA Delete is for data protection, not durability.

Answer

Enable cross-region replication to a bucket in another Region.

Answer

Use S3 One Zone-IA storage class.

Answer

Enable MFA Delete on the bucket.