DVA-C02 Exam Dumps - AWS Certified Developer - Associate

Requirement Summary:

Lambda function:

Retrieves an item from DynamoDB

Updates its attributes or creates it if it does not exist

Has primary key

Needs minimum required IAM permissions

Analysis of Required Permissions:

To get an item and update it or create it if it doesn't exist, the Lambda function must use the **PutItem** or **UpdateItem** API, and read with **GetItem**.

Valid API options:

GetItem: Read the item from the table.

UpdateItem: Update existing item attributes or insert if it doesn't exist (with UpdateExpression and ConditionExpression).

When UpdateItem is used without a conditional check for existence, it can create a new item if it does not exist (acts like upsert).

DescribeTable: (Optional) Used if you need table metadata (not strictly required here).

Evaluate the Choices:

Option A:

DeleteItem – Not needed

GetItem –

PutItem – (can create/replace but not partial update)

Close, but PutItem overwrites the full item, not update-in-place. Acceptable, but UpdateItem is better suited.

Option B:

UpdateItem – Required to modify attributes or insert new item

GetItem – Required to check existence or read data

DescribeTable – Optional, but not harmful

BEST FIT – Matches the update-or-create logic.

Option C:

GetRecords – This is used for DynamoDB Streams, not standard GetItem

PutItem –

UpdateTable – Used to change table settings, not data manipulation

Incorrect usage context

Option D:

UpdateItem, GetItem, PutItem – all valid

But UpdateItem alone is sufficient; including PutItem might not be necessary Also, image is faded (possibly invalid), and it's redundant

UpdateItem API: https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html

PutItem vs UpdateItem: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WorkingWithItems.html

IAM actions for DynamoDB: https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazondynamodb.html

Amazon Cognito user pools support Lambda triggers, which are custom functions that can be executed at various stages of the user pool workflow. A post authentication Lambda trigger can be used to perform custom actions after a user is authenticated, such as sending an email notification. Amazon SES is a cloud-based email sending service that can be used to send transactional or marketing emails. A Lambda function can use the Amazon SES API to send an email to the user’s email address after the user logs in successfully. Reference: Post authentication Lambda trigger

The requirement is to search for partial matches of email_address but scoped to a specific customer_type. In DynamoDB, efficient partial matching is performed with a Query on a sort key using the begins_with() condition. However, Query requires that the partition key be specified exactly, so we need an index where customer_type can be used as the partition key, and email_address can be used as the sort key for prefix matching.

A Global Secondary Index (GSI) can be added to an existing table without recreating it, and it can use a different partition key and sort key from the base table. Option A correctly proposes a GSI with:

Partition key: customer_type

Sort key: email_address

Then the Lambda can run a Query on the GSI like: customer_type = :ct AND begins_with(email_address, :prefix) which returns emails that start with the typed prefix for that customer type.

Option B is wrong because it keeps email_address as the partition key. That would require an exact email value (not a prefix) to Query, and you cannot do begins_with on a partition key; begins_with is for sort keys.

Options C and D are invalid because Local Secondary Indexes (LSIs) must share the same partition key as the base table (here, email_address). You cannot create an LSI with customer_type or job_title as the partition key when the table partition key is email_address.

Therefore, adding a GSI (customer_type PK, email_address SK) and querying it with begins_with is the correct solution.

To rotate database credentials without downtime, Secrets Manager recommends the alternating users (dual user) rotation strategy. With a single-user strategy, Secrets Manager changes the password for the same database user that the application is actively using. If the application continues using cached/old credentials during rotation, authentication failures and downtime can occur.

With the alternating users strategy, two database users exist (often named something like appuser and appuser_clone). Secrets Manager alternates which user is “active” in the secret. During rotation, Secrets Manager updates the inactive user’s password, verifies it, updates the secret to point to the newly updated user, and then (optionally) retires the old credentials. This approach minimizes disruption because there is always one known-good credential set while the other is being updated.

The question specifically requires regular rotation using Secrets Manager. That is achieved by enabling automatic rotation on the secret with a schedule (for example, every 30/60/90 days). Automatic rotation invokes the rotation Lambda (AWS-provided or configured) and performs the workflow without manual intervention.

Option D combines both requirements: automatic rotation plus the alternating users strategy for high availability and no downtime.

Option B mentions alternating users but “managed rotation” is not the standard term used in these choices as the primary differentiator—automatic rotation is the necessary capability to rotate regularly without manual effort.

Options A and C (single user) are more likely to cause downtime during rotation.

Therefore, configure automatic rotation with the alternating users rotation strategy.

Principle of Least Privilege: Granting specific permissions through an IAM role is more secure than directly attaching policies to a function or using root user credentials.

IAM Roles for Lambda: Designed to provide temporary credentials to Lambda functions, enhancing security.

Reusability: The existing IAM policy ensures the correct S3 and DynamoDB access is granted.

For rapid prototyping with the least operational overhead, Lambda function URLs are the best fit. A Lambda function URL provides a built-in HTTPS endpoint directly in front of a Lambda function, allowing the frontend team to invoke each endpoint without requiring additional infrastructure. This is ideal when the overall architecture is not finalized and the team needs a quick way to test.

AWS describes Lambda function URLs as a simple way to “add an HTTPS endpoint to your Lambda function” without requiring API Gateway, load balancers, or custom proxy layers. This substantially reduces setup time and avoids the operational tasks associated with provisioning, configuring, and managing an API layer during early-stage development.

Option B (API Gateway REST API) introduces more operational overhead: creating resources, methods, integrations, deployments, stages, and potentially authorization and throttling configuration. API Gateway is powerful, but it is more than needed for quick endpoint testing.

Option C (AppSync) is designed for GraphQL-based APIs and requires schema design and resolvers. That is unnecessary complexity for simply testing three Lambda-backed endpoints.

Option D (ECS proxy) adds the most operational burden because it requires container orchestration, networking, scaling, and patching—completely misaligned with “least operational overhead.”

Therefore, the fastest and simplest approach is to create a function URL per Lambda endpoint, allowing immediate testing from the frontend with minimal additional AWS configuration.

Requirement Summary:

Simple REST endpoint for weather data

Light backend usage (POC, testing)

Wants caching support to reduce backend calls

Must be cost-effective

Evaluate Options:

B: Lambda + API Gateway + SAM

Serverless = No idle costs

API Gateway can enable caching (response caching at endpoint level)

SAM makes deployment simple and repeatable

Perfect for low-traffic testing

A: EKS + API Gateway

High overhead

Not cost-effective for POC/testing

C: ECS + API Gateway

Similar to A: Container orchestration not needed for light REST endpoint

D: Elastic Beanstalk + ALB + Lambda

Overly complex and does not directly expose Lambda

Beanstalk better suited for full apps, not small REST functions

ï‚· AWS SAM: https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/what-is-sam.html

ï‚· API Gateway caching: https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-caching.html

ï‚· Serverless Best Practices: https://docs.aws.amazon.com/lambda/latest/dg/best-practices.html