DOP-C02 Resilient Cloud Solutions Practice Question
A company is building a serverless application using AWS Lambda, Amazon API Gateway, and Amazon DynamoDB. The application must be resilient to sudden spikes in traffic without manual intervention. Which combination of services should be used?
⚠ Common exam trap
A common mix-up: candidates confuse 'provisioned concurrency' (Option B) with 'reserved concurrency' (Option A), mistakenly believing pre-warming instances handles spikes, when in fact reserved concurrency guarantees capacity but does not reduce cold starts, and provisioned concurrency is for latency, not burst resilience.
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
✓
API Gateway with throttling, Lambda with reserved concurrency, and DynamoDB auto scaling.
It combines API Gateway throttling to absorb traffic spikes by queuing or rejecting excess requests, Lambda reserved concurrency to guarantee execution capacity for the function, and DynamoDB auto scaling to adjust read/write capacity based on demand. This triad ensures the application remains available and responsive under sudden load without manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
API Gateway with throttling, Lambda with reserved concurrency, and DynamoDB auto scaling.
Why this is correct
This combination directly addresses a demand spike: API Gateway throttling imposes a maximum request rate per client or across the API, preventing a flood from reaching Lambda. Reserved concurrency allocates a guaranteed number of Lambda executions, insulating the function from account-level throttling and ensuring the spikes are absorbed within the reserved ceiling. DynamoDB auto scaling adjusts provisioned read/write capacity based on live utilization, so the database keeps pace without manual intervention.
- ✗
API Gateway with usage plans, Lambda with provisioned concurrency, and DynamoDB on-demand.
Why it's wrong here
Usage plans are primarily for quota and rate limits per API key, which manage consumer access rather than protecting the system from a sudden burst. Provisioned concurrency pre-initializes Lambda execution environments to avoid cold start latency, but it does not cap how many invocations can occur, so a spike can still exceed both the provisioned and on-demand concurrency, causing throttling. DynamoDB on-demand does handle unpredictable spikes but carries a higher per-request cost than provisioned capacity with auto scaling, making it inefficient for a steady baseline with occasional peaks.
- ✗
API Gateway with WAF, Lambda with function URLs, and DynamoDB Accelerator (DAX).
Why it's wrong here
AWS WAF is a firewall that filters malicious web traffic and mitigates DDoS, but it offers no control over compute or database capacity during a surge. Lambda function URLs expose a function directly over HTTPS, bypassing API Gateway features like throttling and request validation, which are essential for managing burst load. DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency and read-heavy costs, yet it does nothing to scale write capacity or Lambda concurrency, so the core scaling problem remains unsolved.
- ✗
API Gateway with caching, Lambda with no concurrency limits, and DynamoDB global tables.
Why it's wrong here
API Gateway caching stores backend responses to serve repeated identical requests, which reduces backend load for static content but does not protect the stack during a spike of unique or dynamic traffic. With no concurrency limits, the Lambda function is subject to the AWS account default concurrency limit, so a sharp spike triggers '429 Too Many Requests' throttling errors rather than gracefully scaling. DynamoDB global tables replicate data across AWS regions for high availability and disaster recovery, not for handling a sudden regional demand increase, leaving the target table with potentially insufficient capacity.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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Same concept, more angles
1 more way this is tested on DOP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is building a serverless application using AWS Lambda, Amazon API Gateway, and Amazon DynamoDB. The application is expected to have unpredictable traffic patterns. The DevOps team needs to ensure that the application can handle sudden spikes in traffic without throttling. Which TWO actions should the team take? (Choose TWO.)
medium- ✓ A.Use DynamoDB on-demand capacity mode for the table.
- ✓ B.Configure Lambda provisioned concurrency to keep a set number of execution environments warm.
- C.Configure DynamoDB auto scaling with a minimum capacity of 10 read/write capacity units.
- D.Increase the Lambda function timeout to the maximum (15 minutes).
- E.Set API Gateway throttling limits to a high value to prevent throttling.
Why A: DynamoDB on-demand capacity mode automatically scales to handle unpredictable traffic spikes without requiring capacity planning or throttling. This mode charges per request and can accommodate sudden bursts of traffic up to the table's previous peak, making it ideal for serverless applications with variable workloads.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DOP-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 DOP-C02 exam.