How to Orchestrate AWS Lambda Functions in Sequence with Least Operational Overhead?

DVA-C02 By islever Editorial Last updated Aug 5, 2026

Short answer

C Configure an AWS Step Functions state machine to invoke the Lambda functions in a specific order.

Question

A developer is building an ecommerce application that uses multiple AWS Lambda functions. Each function performs a specific step in a customer order workflow, such as order processing and inventory management. The developer must ensure that the Lambda functions run in a specific order. Which solution will meet this requirement with the LEAST operational overhead?

Configure an Amazon Simple Queue Service (Amazon SQS) queue to contain messages about each step a function must perform. Configure the Lambda functions to run sequentially based on the order of messages in the SQS queue.
Configure an Amazon Simple Notification Service (Amazon SNS) topic to contain notifications about each step a function must perform. Subscribe the Lambda functions to the SNS topic. Use subscription filters based on the step each function must perform.
Configure an AWS Step Functions state machine to invoke the Lambda functions in a specific order. Correct Answer
Configure Amazon EventBridge Scheduler schedules to invoke the Lambda functions in a specific order.

Key Takeaways

This question tests the ability to identify the correct AWS service for workflow orchestration, focusing on the key phrase 'least operational overhead' which points directly to a fully managed serverless solution.

AWS Step Functions provides a serverless orchestration service that coordinates multiple AWS Lambda functions in a defined order with minimal operational overhead, making it the ideal choice for sequential workflow automation.

Common mistake: Candidates often choose Amazon SQS (Option A) because queues can enforce ordering, but SQS requires custom logic within Lambda functions to manage the workflow sequence, significantly increasing operational overhead compared to Step Functions.

Expert Analysis

Understanding the Requirement

The question requires orchestrating multiple AWS Lambda functions in a specific sequential order for an ecommerce workflow (order processing → inventory management) with the LEAST operational overhead. This is a classic workflow orchestration scenario.

Why AWS Step Functions is Correct (Option C)

AWS Step Functions is a fully managed serverless orchestration service specifically designed for coordinating multiple AWS services into business workflows. Key advantages include:

Visual workflow definition using Amazon States Language (ASL)
Built-in sequencing — you explicitly define the order of execution
Automatic error handling with retry and catch mechanisms
Zero infrastructure management — no servers, queues, or polling logic to maintain
Native Lambda integration — invoke functions directly as state machine tasks

As community members correctly noted: "Orchestration is done by Step Functions" and "LEAST operational overhead, its Step Functions."

Why the Other Options Are Incorrect

Option A (Amazon SQS): While SQS FIFO queues preserve message ordering, you would need to build custom orchestration logic inside each Lambda function to trigger the next step. This introduces significant operational overhead — error handling, retries, dead-letter queues, and sequencing logic all fall on the developer.

Option B (Amazon SNS): SNS is a pub/sub notification service, not an orchestration tool. All subscribed Lambda functions would be triggered simultaneously (fan-out), not sequentially. Subscription filters only control which messages a subscriber receives, not execution order.

Option D (Amazon EventBridge Scheduler): EventBridge Scheduler is designed for time-based scheduling (cron-like triggers), not for coordinating dependent workflow steps. It cannot express dependencies like "run inventory management only after order processing completes successfully."

Key Takeaway

Whenever an exam question mentions orchestration, workflow, specific order, or sequential execution of Lambda functions, immediately think AWS Step Functions. The phrase "LEAST operational overhead" further confirms a fully managed serverless service is required.

Official Reference

These links open the official vendor documentation in a new tab.

Exam Strategy

When you see 'LEAST operational overhead' combined with workflow orchestration or sequential execution of Lambda functions, AWS Step Functions is almost always the correct answer. Eliminate SQS and SNS immediately as they require custom orchestration logic or run tasks in parallel.

Community Votes

100%

100% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

ShakthiGCP 👍 3 Answered C

Orchestration is done by Step functions
YUICH 👍 1 Answered C

C. AWS Step Functions AWS Step Functions is designed to orchestrate workflows, making it ideal for ensuring Lambda functions execute in a specific order. It allows you to define a state machine that explicitly specifies the sequence of execution, handles errors, and minimizes operational overhead. This makes it the most suitable choice.
xdeveloper 👍 1 Answered C

LEAST operational overhead , its Step Functions.

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