DVA-C02 Development with AWS Services Practice Question
A company is running a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application uses Amazon ElastiCache for session state. Recently, users are experiencing intermittent session timeouts and slow page loads. The developer suspects the issue is related to the ElastiCache cluster. Which THREE actions should the developer take to troubleshoot and resolve the issue? (Choose THREE.)
⚠ Common exam trap
Many exam-takers confuse high-availability features like Multi-AZ replication or encryption with performance fixes, when in fact they address durability and security, not throughput or latency.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Monitor the ElastiCache cluster's CPU utilization and cache hit ratio in CloudWatch.
Option A is correct because CloudWatch metrics such as CPUUtilization and CacheHits/CacheMisses (cache hit ratio) directly reveal whether the ElastiCache cluster is saturated or failing to serve cached session data, which would cause the intermittent timeouts and slow loads. Option C is correct because if monitoring shows sustained high CPU or memory pressure, vertically scaling to a larger node type or horizontally adding nodes/shards increases capacity and restores consistent session-state performance. Option D is correct because uneven key distribution or poor cache key design can create hot shards/keys, leading to throttling and latency spikes even when overall cluster capacity looks adequate, so reviewing key design and shard balance addresses the root cause. Option B does not belong because enabling encryption in transit is a security hardening measure and does not resolve performance or session-timeout issues. Option E does not belong because Multi-AZ replication improves availability/failover, not the intermittent latency and timeout symptoms described.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Monitor the ElastiCache cluster's CPU utilization and cache hit ratio in CloudWatch.
Why this is correct
Monitoring ElastiCache CPU utilization in CloudWatch helps identify if the cluster is under-provisioned or experiencing heavy processing load, indicating a need for scaling. Concurrently, tracking the cache hit ratio is vital; a low hit ratio suggests that the application is frequently missing cached data, leading to increased latency as requests fall back to the origin database. These metrics collectively provide actionable insights into cache efficiency and potential performance bottlenecks.
- ✗
Enable Encryption in transit for the ElastiCache cluster.
Why it's wrong here
Enabling encryption in transit for an ElastiCache cluster, while a critical security best practice, primarily protects data confidentiality as it moves between clients and the cache nodes. This feature, typically implemented using TLS, does not inherently improve the application's performance or reduce latency. In fact, the overhead of encryption and decryption can introduce a marginal increase in CPU utilization, making it unrelated to solving performance bottlenecks.
- ✓
Scale the ElastiCache cluster by adding more nodes or using a larger node type.
Why this is correct
Scaling an ElastiCache cluster directly addresses performance issues by increasing its capacity and processing power. Adding more nodes (horizontal scaling) distributes the load across a larger pool of resources, enhancing throughput and reducing contention. Alternatively, upgrading to a larger node type (vertical scaling) provides more CPU, memory, and network bandwidth per node, which can significantly improve individual request processing times and overall cluster responsiveness under heavy load.
- ✓
Review the application's cache key design and ensure that data is evenly distributed across shards.
Why this is correct
A well-designed cache key strategy is fundamental for optimal ElastiCache performance, particularly in sharded clusters like Redis. Ensuring data is evenly distributed across shards prevents "hot shards," where a disproportionate amount of requests or data concentrates on a single node, leading to resource exhaustion and performance degradation for that specific shard. An effective key design, often involving hashing, spreads the load, maximizing the cluster's aggregate capacity and improving overall responsiveness.
- ✗
Enable Multi-AZ replication for the ElastiCache cluster.
Why it's wrong here
Enabling Multi-AZ replication for an ElastiCache cluster is a high availability strategy designed to provide automatic failover to a replica in a different Availability Zone if the primary node becomes unavailable. While crucial for business continuity and fault tolerance, this configuration does not directly enhance the performance of the application or the cache's read/write throughput. Its primary purpose is resilience, not performance optimization under normal operating conditions.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DVA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DVA-C02 exam.