AWS Developer Associate DVA study guide DVA-C02

1. Exam Introduction
**1.1 Exam Details**
The AWS Certified Developer – Associate (DVA) certification is made up of scenario-based questions that are either multiple-choice or multiple-response. The former has only one correct answer whilst the latter can have two or more correct responses out of five or more options. Take extra care when reading the question to determine which of the two question types you are being presented with as this can be a common tripping point for candidates.

• Exam code DVA-C02
• Number of questions 65
• Score range 100-1000
• Passing score 720/1000
• Time Limit 2 hours 10 minutes (130 minutes)[]
• Format Scenario-based - Multiple choice/Multiple response

**1.2 Exam domains
**The DVA exam can be broken down into 4 different domains. Each domain has a corresponding weight and topic coverage. This breakdown can be seen in Figure 1:

Figure 1 - Breakdown of the 4 different domains for the DVA exam
Domain 1: Development with AWS Services (32%)
1.1 Develop code for applications hosted on AWS
1.2 Develop code for AWS Lambda
1.3 Use data stores in application development.
1.4 Deploy serverless applications

Domain 2: Security (26%)
2.1 Implement authentication and/or authorization for applications and AWS services.
2.2 Implement encryption by using AWS services.
2.3 Manage sensitive data in application code.

Domain 3: Deployment (24%)
3.1 Prepare application artifacts to be deployed to AWS.
3.2 Test applications in development environments.
3.3 Automate deployment testing
3.4 Deploy code by using AWS CI/CD services.

Domain 4: Troubleshooting and Optimization
(18%)
4.1 Assist in a root cause analysis.
4.2 Instrument code for observability.
4.3 Optimize applications by using AWS services and features.

**1.3.Exam scoring
**A minimum scaled score of 720 is needed to pass the DVA exam with the range of scores being 100-1000. Immediately upon completing the exam a pass or fail notification will be show on the testing application.
A complete score report is sent to the email address that was registered within 5 business days. The score report contains a breakdown of your performance over the 4 domains by way of either meeting competency or not.

**2.Study Materials
**2.1.Resources

Collation of study material

**Description **Priority Type Cost
Cloud Academy - AWS Developer – Associate (DVA-C02) Certification Preparation Highly Recommended Video Course Free for Community Builder
A Cloud Guru - AWS Certified Developer - Associate Recommended Video Course Free with A Cloud Guru subscription
Udemy Course - AWS DVA by Stephane Maarek Recommended Video Course Paid
Tutorials Dojo Jon Bonso - AWS Certified DVA - Practice Exams Recommended Practice Exam Paid
Whizlab - CDVA Practice Tests Optional Practice Exam Paid
Exam Readiness: AWS Certified Developer – Associate (Digital) Recommended Practice Exam Paid
AWS SkillBuilder AWS Certified Developer - Associate Official Practice Question Set (DVA-C02 - English) Recommended Practice Exam Free
AWS – Official Exam Study Guide Recommended Supplementary Free
Tutorial Dojo - Cheat Sheets Optional Supplementary Free
Neil Davis - Cheat Sheets Optional Supplementary Free
AWS Whitepapers, FAQ, Documentation Optional Supplementary Free

*3.Exam Scenarios
*
Scenario Solution

• Domain 1: Development with AWS Services

• Provides a time-ordered sequence of item level changes in any DynamoDB table DynamoDB Streams.

• Using AWS Lambda to process records in a Kinesis Data streams that has 100 active shards. The Lambda function takes around 10 seconds to process the data, and the stream is receiving 50 new items per second. What can you say about the number of concurrent Lambda functions? There will be at most 100 Lambda functions (as 100 shards).

• Uploaded large files to S3 (over 4GB), how do you minimize upload time? Multipart upload API.

• Unresponsive MySQL RDS database. How do you collect all SQL statements that took longer to execute for troubleshooting? Enable slow query log in RDS.

• Slow log in times for users in your web app hosted behind a CloudFront distribution. Use Lambda@Edge to execute the authentication process closer to the user.

• How do you reuse the same Lambda function for multiple stages of your API but pass in different variables depending on the stage? Use stage variables.

• Record events in an SWF Workflow execution. Use markers.

• Consistency that DynamoDB global secondary indexes support. Eventual consistency only.

• AWS Service for defining IaC specific to serverless services. AWS SAM.

• Can APIs that are created with API Gateway support http? No, all APIs created by Amazon API Gateway expose HTTPS endpoints only.

• Enable cross-device syncing of user profile data in a mobile game? Cognito Sync

• How could you increase the capacity of an Amazon Kinesis Data Stream? Split every shard in the stream

• High number of read operations in an RDS database which affects the website's performance, quickly resolve the issue with minimal cost and code change Create an RDS Read Replica instance and configure the application to use this for read queries

• Improve an application’s performance by reducing a DynamoDB database’s response times down to microseconds Use Amazon DynamoDB Accelerator (DAX)
  **- Domain 2: Security

• Serverless app is composed of several Lambdas reading from RDS. These functions must share the same connection string that should be encrypted to improve data security. Create a Secure String Parameter using the AWS Systems Manager Parameter store.

• Request header to use to enforce S3 server-side encryption. x-amz-server-side-encryption.

• Safest way to grant an application hosted in EC2 permission to upload data to S3 Use an IAM Role to grant the application the necessary permissions.

• Using API Gateway Lambda Authorizer to provide authentication for every API request. What method should be used to implement authentication like SAML or OAuth. Token-Based Authorization.

• Describe the process of envelope encryption for encryption keys. Encrypt plaintext data with a data key, then encrypt the data key with a top-level plaintext master key.

• In the AppSpec file in CodeDeploy, which deployment lifecycle event allows you to run a task before the traffic is shifted to the deployed app? BeforeAllowTraffic.

• When managing a company’s IAM resources, what are some best practices in managing security? Grant only the permissions required by the resource to perform a task, and delete root user access keys.

• 2 services that can be used to safely import a SSL/TLS certificate. AWS Certificate Manager and IAM certificate store.

• Most appropriate service to store RDS database credentials, where they will be encrypted and rotated on a regular basis? AWS Secrets Manager (allows automatic rotation).

• How can you improve the performance of an RDS database whose performance slows down whenever there is a surge in requests that use the same SQL read queries? Create Read Replicas

• Implement database caching using ElastiCache

• The average time that it takes for producers to send a new message to a Standard SQS queue is 40 seconds. Which polling setting is the most efficient way for the application to query the new messages from the queue? Long Polling
  **- Domain 3: Deployment

• Internal Web App on EC2 instances need to access an S3 Bucket. Create a VPC endpoint for S3.

• Deployment to Lambda function using CodeDeploy, need to shift 10% of traffic to new version in the first increment and the other 90% 5 minutes later. Canary Deployment.

• You want to deploy a serverless app using CloudFormation, the AWS SAM syntax should be used to declare resources. Include the Transform section in CloudFormation specifying the version of SAM to use.

• Amount of RCUs for a DynamoDB table, each data has an average size of 3.5KB and will send 150 eventually consistent reads per second. 75. (each read does up to 4KB per RCU, so 1 per data = 150 RCU. Divide by 2 as the reads are eventually consistent)

• Application that will be hosted in an ECS cluster, tasks must be placed based on the least available amount of CPU or memory. Use the binpack placement strategy.

• A developer is instructed to set up a new serverless architecture. The new architecture should allow the developer to locally build, test, and debug serverless applications. Use AWS Serverless Application Model (AWS SAM).

• A developer will do iterative tests on an app hosted on Elastic Beanstalk and therefore needs to deploy code changes and view them as quickly as possible. Use All at Once Deployment.

• Deploy a update to an app hosted on EC2 instances, the update needs to be on a new set of instances. Immutable deployment.

• CloudFormation helper script to install packages, create files and start services. cfn-init
  **- Domain 4:Troubleshooting and Optimization

• How can you capture information about the IP traffic going to and from network interfaces in your VPC? -- Create VPC flow log.

• A service to trace and analyse user requests as they go through an Amazon API Gateway API and eventually through to the underlying services in an application. -- AWS X-Ray

• What is the lifetime of all data in a DynamoDB Stream? -- 24 hours

• How can you ensure that all of the API calls to your AWS resources are logged and stored? Use CloudTrail

• True or False: By default, you can see the CPU utilization of EC2 instances but not the memory utilization? True – CloudWatch does not track memory utilization by default.

• (Install a CloudWatch agent in your EC2 instances to track memory utilization.)

• You need to manually increase the current number of instances to 20 to prepare for a temporary influx of requests, which Auto Scaling group option will you set to 20? Desired capacity

• Which of the following services should you implement to mitigate SQL injection attempts and cross-site scripting attacks? AWS WAF

**3.2.Compared Services
**The following is the service list which may appear in the exam from time to time. It is crucial to understand the key features of these services and their differences.

• S3 vs EBS vs EFS
• S3 Standard vs S3 Standard-IA vs S3 One Zone-IA vs S3 Intelligent Tiering vs Glacier
• S3 Pre-Signed URLS vs CloudFront Signed URLS vs Origin Access Identity
• S3 Transfer Acceleration vs Direct Connect vs VPN vs Snowball Edge vs Snowmobile
• AWS CloudTrail vs CloudWatch
• Security Group vs NACL
• EBS-SSD vs HDD
• Elastic Beanstalk vs CloudFormation vs OpsWorks vs CodeDeploy
• Global Secondary Index vs Local Secondary Index
• CloudWatch Agent vs SSM Agent vs Custom Daemon Scripts
• Amazon SWF vs AWS Step Functions vs Amazon SQS
• Application vs Network vs Classic vs Gateway Load Balancers
• AWS DataSync vs Storage Gateway
• RDS vs DynamoDB
• RDS vs Aurora
• EC2 Container Services ECS vs Lambda
• SNI Custom SSL vs Dedicated IP Custom SSL
• EC2 Instance Health Check vs ELB Health Check vs Auto Scaling and Custom Health Check
• Multi-AZ deployments vs Multi-Region deployments vs Read Replicas

**4 Extra time for the exam
If English is your second language, you can request for ESL+30 mins before booking the exam from certmetrics > Request Exam Accomodations and wait for the approval. Once it is approved, this will apply to all AWS existing exams.

*Note: this needs to be done before your exam registration.
*
Good Luck for your coming DVA exam!