Question 156 of 1,040
Design High-Performing ArchitecturesmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is to add Amazon DAX as a caching layer in front of DynamoDB and route repeated read operations through it. This is correct because DAX is a fully managed, in-memory cache designed specifically for DynamoDB, providing microsecond read latency by storing the results of frequent GetItem and Query requests. When many clients repeatedly request the latest status for the same devices, DAX offloads those reads from the underlying table, reducing consumed read capacity units and eliminating the latency of repeated disk fetches—all without altering the existing partition key or partitioning model. On the SAA-C03 exam, this scenario tests your understanding of caching strategies for read-heavy workloads where the partition distribution is already healthy; a common trap is to suggest increasing read capacity or adding a global secondary index, but those don’t address the root cause of repeated identical requests. Remember the memory tip: “DAX for repeated reads, not for writes or hot partitions”—it’s your go-to when the bottleneck is repetitive, cacheable queries on the same items.

SAA-C03 Design High-Performing Architectures Practice Question

This SAA-C03 practice question tests your understanding of design high-performing architectures. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A DynamoDB table stores device status items. The partition key is deviceId, and the partition distribution is healthy (no single partition dominates). However, during peak periods the application experiences high read latency because many clients repeatedly request the latest status for the same devices. Which action best improves read latency without changing the DynamoDB partitioning model?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "best"

    Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

Question 1mediummultiple choice
Read the full NAT/PAT explanation →

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

Add Amazon DAX as a caching layer in front of DynamoDB and route repeated read operations through DAX.

Amazon DAX is a fully managed, in-memory cache for DynamoDB that provides microsecond read latency. By caching the results of repeated GetItem and Query requests for the same device status items, DAX offloads read traffic from the underlying DynamoDB table, reducing the number of read capacity units consumed and eliminating the latency caused by repeated fetches from disk. This directly addresses the high read latency during peak periods without altering the existing partition key or partitioning model.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Add Amazon DAX as a caching layer in front of DynamoDB and route repeated read operations through DAX.

    Why this is correct

    Amazon DAX is an in-memory caching layer for DynamoDB that accelerates repeated reads. When many clients request the same items (for example, “latest status” point reads by deviceId), DAX can serve cached responses directly, reducing round trips to DynamoDB and lowering read latency during peak periods.

    Clue confirmation

    The clue word "best" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Change the partition key to a random value for each request to eliminate hot partitions.

    Why it's wrong here

    The scenario states partition distribution is already healthy, so randomizing the partition key does not target the actual problem (repeat reads of the same items). It also breaks the access pattern because the application can no longer reliably request items by deviceId, and it can reduce usability and query correctness.

  • Increase write capacity only, because writes generally determine read latency in DynamoDB.

    Why it's wrong here

    Write capacity does not directly address read latency for repeatedly accessed items. Read latency is primarily influenced by read capacity, item size, network latency, and whether reads are being accelerated via caching (such as DAX). Increasing writes may increase overall workload contention without fixing the repeated-read issue.

  • Create an additional Global Secondary Index (GSI) and read exclusively from the index to accelerate reads.

    Why it's wrong here

    A GSI can support alternate query patterns or access paths, but it does not provide caching for repeated point reads. Creating a GSI changes how items are accessed and billed; it is not as direct as using DAX to reduce latency for repeated reads of the same keys.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates may think a GSI can magically speed up reads, but GSIs do not provide caching and still read from the same storage layer, so they do not reduce latency for repeated identical queries.

Trap categories for this question

  • Scenario analysis trap

    The scenario states partition distribution is already healthy, so randomizing the partition key does not target the actual problem (repeat reads of the same items). It also breaks the access pattern because the application can no longer reliably request items by deviceId, and it can reduce usability and query correctness.

Detailed technical explanation

How to think about this question

DAX acts as a write-through cache, meaning that when data is written to DynamoDB, it is also written to the cache, ensuring consistency for subsequent reads. Under the hood, DAX uses an in-memory engine that stores frequently accessed items, and it automatically evicts least-recently-used data when memory is full. In a real-world scenario, a fleet management system where thousands of clients poll the latest status of the same 100 devices every second would see a dramatic reduction in read latency from single-digit milliseconds to microseconds by using DAX, while also reducing DynamoDB read costs.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this SAA-C03 question test?

Design High-Performing Architectures — This question tests Design High-Performing Architectures — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Add Amazon DAX as a caching layer in front of DynamoDB and route repeated read operations through DAX. — Amazon DAX is a fully managed, in-memory cache for DynamoDB that provides microsecond read latency. By caching the results of repeated GetItem and Query requests for the same device status items, DAX offloads read traffic from the underlying DynamoDB table, reducing the number of read capacity units consumed and eliminating the latency caused by repeated fetches from disk. This directly addresses the high read latency during peak periods without altering the existing partition key or partitioning model.

What should I do if I get this SAA-C03 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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This SAA-C03 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 SAA-C03 exam.