High Availability Flashcards
7 cards from real AWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 High Availability flashcards as text
A CloudFormation stack update fails midway through and needs to roll back. Which resource types may NOT be automatically rolled back by CloudFormation?
Answer: S3 buckets with data and some stateful resources like RDS with deletion policies
S3 buckets containing objects and RDS instances with Retain deletion policies cannot be automatically deleted during rollback, leaving partial state.
Which ALB feature helps maintain high availability by routing requests away from unhealthy targets without any DNS changes?
Answer: Target group health checks with automatic deregistration of unhealthy targets
ALB continuously performs health checks and stops routing traffic to unhealthy targets, automatically recovering when targets pass health checks again.
A DevOps engineer needs to implement a canary deployment for a Lambda function to validate a new version before full cutover. Which feature supports this natively?
Answer: Lambda aliases with weighted traffic shifting between versions
Lambda aliases support traffic shifting by assigning weights between two versions, enabling canary or linear deployment strategies natively.
An SQS queue is used to decouple a producer and consumer. What configuration prevents message loss if the consumer service becomes temporarily unavailable?
Answer: Configure a Dead Letter Queue (DLQ) and set appropriate message retention period
A DLQ captures messages that fail processing after maximum retries, while message retention period keeps messages available during consumer downtime.
Which EC2 Auto Scaling policy type is most appropriate for predictably increasing traffic patterns, such as a daily business hours spike?
Answer: Scheduled scaling action
Scheduled scaling actions preemptively scale out before a known traffic increase, avoiding latency from reactive scaling during the spike.
A stateful application requires session persistence across multiple EC2 instances behind an ALB. Which solution maintains high availability without a single point of failure?
Answer: Store sessions in ElastiCache Redis with Multi-AZ replication enabled
ElastiCache Redis with Multi-AZ stores sessions externally and replicates them, allowing any EC2 instance to serve any user without sticky routing.
In AWS CodePipeline, which action type can be used to implement a manual approval gate before deploying to production, ensuring human review?
Answer: Manual approval action in an Approval action group
CodePipeline's manual approval action pauses the pipeline and sends notifications via SNS, requiring a designated approver to proceed.