AWS Certified Developer Associate Exam Preparation: Questions and Answers Dump

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What is the AWS Certified Developer Associate Exam?

This AWS Certified Developer-Associate Examination is intended for individuals who perform a
Developer role. It validates an examinee’s ability to:

  • Demonstrate an understanding of core AWS services, uses, and basic AWS architecture best practices.
  • Demonstrate proficiency in developing, deploying, and debugging cloud-based applications using AWS.

There are no prerequisites for taking the Developer-Associate examination, but here are the recommended AWS Knowledge:

  • One or more years of hands-on experience developing and maintaining an AWS based application
  • In-depth knowledge of at least one high-level programming language
  • Understanding of core AWS services, uses, and basic AWS architecture best practices
  • Proficiency in developing, deploying, and debugging cloud-based applications using AWS
  • Ability to use the AWS service APIs, AWS CLI, and SDKs to write applications
  • Ability to identify key features of AWS services
  • Understanding of the AWS shared responsibility model
  • Understanding of application lifecycle management
  • Ability to use a CI/CD pipeline to deploy applications on AWS
  • Ability to use or interact with AWS services
  • Ability to apply a basic understanding of cloud-native applications to write code
  • Ability to write code using AWS security best practices (e.g., not using secret and access keys in the code, instead using IAM roles)
  • Ability to author, maintain, and debug code modules on AWS
  • Proficiency writing code for serverless applications
  • Understanding of the use of containers in the development process

To succeed with the real exam, do not memorize the answers below. It is very important that you understand why a question is right or wrong and the concepts behind it by carefully reading the reference documents in the answers.

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AWS Certified Developer – Associate Practice Questions And Answers Dump

Q0: Your application reads commands from an SQS queue and sends them to web services hosted by your
partners. When a partner’s endpoint goes down, your application continually returns their commands to the queue. The repeated attempts to deliver these commands use up resources. Commands that can’t be delivered must not be lost.
How can you accommodate the partners’ broken web services without wasting your resources?

  • A. Create a delay queue and set DelaySeconds to 30 seconds
  • B. Requeue the message with a VisibilityTimeout of 30 seconds.
  • C. Create a dead letter queue and set the Maximum Receives to 3.
  • D. Requeue the message with a DelaySeconds of 30 seconds.

C. After a message is taken from the queue and returned for the maximum number of retries, it is
automatically sent to a dead letter queue, if one has been configured. It stays there until you retrieve it for forensic purposes.

Reference: Amazon SQS Dead-Letter Queues

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Q1: A developer is writing an application that will store data in a DynamoDB table. The ratio of reads operations to write operations will be 1000 to 1, with the same data being accessed frequently.
What should the Developer enable on the DynamoDB table to optimize performance and minimize costs?

  • A. Amazon DynamoDB auto scaling
  • B. Amazon DynamoDB cross-region replication
  • C. Amazon DynamoDB Streams
  • D. Amazon DynamoDB Accelerator

D. The AWS Documentation mentions the following:

DAX is a DynamoDB-compatible caching service that enables you to benefit from fast in-memory performance for demanding applications. DAX addresses three core scenarios

  1. As an in-memory cache, DAX reduces the response times of eventually-consistent read workloads by an order of magnitude, from single-digit milliseconds to microseconds.
  2. DAX reduces operational and application complexity by providing a managed service that is API-compatible with Amazon DynamoDB, and thus requires only minimal functional changes to use with an existing application.
  3. For read-heavy or bursty workloads, DAX provides increased throughput and potential operational cost savings by reducing the need to over-provision read capacity units. This is especially beneficial for applications that require repeated reads for individual keys.

Reference: AWS DAX

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Q2: You are creating a DynamoDB table with the following attributes:

  • PurchaseOrderNumber (partition key)
  • CustomerID
  • PurchaseDate
  • TotalPurchaseValue

One of your applications must retrieve items from the table to calculate the total value of purchases for a
particular customer over a date range. What secondary index do you need to add to the table?

  • A. Local secondary index with a partition key of CustomerID and sort key of PurchaseDate; project the
    TotalPurchaseValue attribute
  • B. Local secondary index with a partition key of PurchaseDate and sort key of CustomerID; project the
    TotalPurchaseValue attribute
  • C. Global secondary index with a partition key of CustomerID and sort key of PurchaseDate; project the
    TotalPurchaseValue attribute
  • D. Global secondary index with a partition key of PurchaseDate and sort key of CustomerID; project the
    TotalPurchaseValue attribute

C. The query is for a particular CustomerID, so a Global Secondary Index is needed for a different partition
key. To retrieve only the desired date range, the PurchaseDate must be the sort key. Projecting the
TotalPurchaseValue into the index provides all the data needed to satisfy the use case.

Reference: AWS DynamoDB Global Secondary Indexes

Difference between local and global indexes in DynamoDB

    • Global secondary index — an index with a hash and range key that can be different from those on the table. A global secondary index is considered “global” because queries on the index can span all of the data in a table, across all partitions.
    • Local secondary index — an index that has the same hash key as the table, but a different range key. A local secondary index is “local” in the sense that every partition of a local secondary index is scoped to a table partition that has the same hash key.
    • Local Secondary Indexes still rely on the original Hash Key. When you supply a table with hash+range, think about the LSI as hash+range1, hash+range2.. hash+range6. You get 5 more range attributes to query on. Also, there is only one provisioned throughput.
    • Global Secondary Indexes defines a new paradigm – different hash/range keys per index.
      This breaks the original usage of one hash key per table. This is also why when defining GSI you are required to add a provisioned throughput per index and pay for it.
    • Local Secondary Indexes can only be created when you are creating the table, there is no way to add Local Secondary Index to an existing table, also once you create the index you cannot delete it.
    • Global Secondary Indexes can be created when you create the table and added to an existing table, deleting an existing Global Secondary Index is also allowed.

Throughput :

  • Local Secondary Indexes consume throughput from the table. When you query records via the local index, the operation consumes read capacity units from the table. When you perform a write operation (create, update, delete) in a table that has a local index, there will be two write operations, one for the table another for the index. Both operations will consume write capacity units from the table.
  • Global Secondary Indexes have their own provisioned throughput, when you query the index the operation will consume read capacity from the index, when you perform a write operation (create, update, delete) in a table that has a global index, there will be two write operations, one for the table another for the index*.

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Q3: When referencing the remaining time left for a Lambda function to run within the function’s code you would use:

  • A. The event object
  • B. The timeLeft object
  • C. The remains object
  • D. The context object

D. The context object.

Reference: AWS Lambda

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Q4: What two arguments does a Python Lambda handler function require?

  • A. invocation, zone
  • B. event, zone
  • C. invocation, context
  • D. event, context

D. event, context
def handler_name(event, context):

return some_value

Reference: AWS Lambda Function Handler in Python

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Q5: Lambda allows you to upload code and dependencies for function packages:

  • A. Only from a directly uploaded zip file
  • B. Only via SFTP
  • C. Only from a zip file in AWS S3
  • D. From a zip file in AWS S3 or uploaded directly from elsewhere

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D. From a zip file in AWS S3 or uploaded directly from elsewhere

Reference: AWS Lambda Deployment Package

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Q6: A Lambda deployment package contains:

  • A. Function code, libraries, and runtime binaries
  • B. Only function code
  • C. Function code and libraries not included within the runtime
  • D. Only libraries not included within the runtime

C. Function code and libraries not included within the runtime

Reference: AWS Lambda Deployment Package in PowerShell

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Q7: You are attempting to SSH into an EC2 instance that is located in a public subnet. However, you are currently receiving a timeout error trying to connect. What could be a possible cause of this connection issue?

  • A. The security group associated with the EC2 instance has an inbound rule that allows SSH traffic, but does not have an outbound rule that allows SSH traffic.
  • B. The security group associated with the EC2 instance has an inbound rule that allows SSH traffic AND has an outbound rule that explicitly denies SSH traffic.
  • C. The security group associated with the EC2 instance has an inbound rule that allows SSH traffic AND the associated NACL has both an inbound and outbound rule that allows SSH traffic.
  • D. The security group associated with the EC2 instance does not have an inbound rule that allows SSH traffic AND the associated NACL does not have an outbound rule that allows SSH traffic.

D. Security groups are stateful, so you do NOT have to have an explicit outbound rule for return requests. However, NACLs are stateless so you MUST have an explicit outbound rule configured for return request.

Reference: Comparison of Security Groups and Network ACLs

AWS Security Groups and NACL

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Q8: You have instances inside private subnets and a properly configured bastion host instance in a public subnet. None of the instances in the private subnets have a public or Elastic IP address. How can you connect an instance in the private subnet to the open internet to download system updates?

  • A. Create and assign EIP to each instance
  • B. Create and attach a second IGW to the VPC.
  • C. Create and utilize a NAT Gateway
  • D. Connect to a VPN

C. You can use a network address translation (NAT) gateway in a public subnet in your VPC to enable instances in the private subnet to initiate outbound traffic to the Internet, but prevent the instances from receiving inbound traffic initiated by someone on the Internet.

Reference: AWS Network Address Translation Gateway

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Q9: What feature of VPC networking should you utilize if you want to create “elasticity” in your application’s architecture?

  • A. Security Groups
  • B. Route Tables
  • C. Elastic Load Balancer
  • D. Auto Scaling

D. Auto scaling is designed specifically with elasticity in mind. Auto scaling allows for the increase and decrease of compute power based on demand, thus creating elasticity in the architecture.

Reference: AWS Autoscalling

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Q10: Lambda allows you to upload code and dependencies for function packages:

  • A. Only from a directly uploaded zip file
  • B. Only from a directly uploaded zip file
  • C. Only from a zip file in AWS S3
  • D. From a zip file in AWS S3 or uploaded directly from elsewhere

D. From a zip file in AWS S3 or uploaded directly from elsewhere

Reference: AWS Lambda

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Q11: You’re writing a script with an AWS SDK that uses the AWS API Actions and want to create AMIs for non-EBS backed AMIs for you. Which API call should occurs in the final process of creating an AMI?

  • A. RegisterImage
  • B. CreateImage
  • C. ami-register-image
  • D. ami-create-image

A. It is actually – RegisterImage. All AWS API Actions will follow the capitalization like this and don't have hyphens in them.

Reference: API RegisterImage

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Q12: When dealing with session state in EC2-based applications using Elastic load balancers which option is generally thought of as the best practice for managing user sessions?

  • A. Having the ELB distribute traffic to all EC2 instances and then having the instance check a caching solution like ElastiCache running Redis or Memcached for session information
  • B. Permenantly assigning users to specific instances and always routing their traffic to those instances
  • C. Using Application-generated cookies to tie a user session to a particular instance for the cookie duration
  • D. Using Elastic Load Balancer generated cookies to tie a user session to a particular instance

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Q13: Which API call would best be used to describe an Amazon Machine Image?

  • A. ami-describe-image
  • B. ami-describe-images
  • C. DescribeImage
  • D. DescribeImages

D. In general, API actions stick to the PascalCase style with the first letter of every word capitalized.

Reference: API DescribeImages

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Q14: What is one key difference between an Amazon EBS-backed and an instance-store backed instance?

  • A. Autoscaling requires using Amazon EBS-backed instances
  • B. Virtual Private Cloud requires EBS backed instances
  • C. Amazon EBS-backed instances can be stopped and restarted without losing data
  • D. Instance-store backed instances can be stopped and restarted without losing data

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C. Instance-store backed images use “ephemeral” storage (temporary). The storage is only available during the life of an instance. Rebooting an instance will allow ephemeral data stay persistent. However, stopping and starting an instance will remove all ephemeral storage.

Reference: What is the difference between EBS and Instance Store?

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Q15: After having created a new Linux instance on Amazon EC2, and downloaded the .pem file (called Toto.pem) you try and SSH into your IP address (54.1.132.33) using the following command.
ssh -i my_key.pem ec2-user@52.2.222.22
However you receive the following error.
@@@@@@@@ WARNING: UNPROTECTED PRIVATE KEY FILE! @ @@@@@@@@@@@@@@@@@@@
What is the most probable reason for this and how can you fix it?

  • A. You do not have root access on your terminal and need to use the sudo option for this to work.
  • B. You do not have enough permissions to perform the operation.
  • C. Your key file is encrypted. You need to use the -u option for unencrypted not the -i option.
  • D. Your key file must not be publicly viewable for SSH to work. You need to modify your .pem file to limit permissions.

D. You need to run something like: chmod 400 my_key.pem

Reference:

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Q16: You have an EBS root device on /dev/sda1 on one of your EC2 instances. You are having trouble with this particular instance and you need to either Stop/Start, Reboot or Terminate the instance but you do NOT want to lose any data that you have stored on /dev/sda1. However, you are unsure if changing the instance state in any of the aforementioned ways will cause you to lose data stored on the EBS volume. Which of the below statements best describes the effect each change of instance state would have on the data you have stored on /dev/sda1?

  • A. Whether you stop/start, reboot or terminate the instance it does not matter because data on an EBS volume is not ephemeral and the data will not be lost regardless of what method is used.
  • B. If you stop/start the instance the data will not be lost. However if you either terminate or reboot the instance the data will be lost.
  • C. Whether you stop/start, reboot or terminate the instance it does not matter because data on an EBS volume is ephemeral and it will be lost no matter what method is used.
  • D. The data will be lost if you terminate the instance, however the data will remain on /dev/sda1 if you reboot or stop/start the instance because data on an EBS volume is not ephemeral.

D. The question states that an EBS-backed root device is mounted at /dev/sda1, and EBS volumes maintain information regardless of the instance state. If it was instance store, this would be a different answer.

Reference: AWS Root Device Storage

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Q17: EC2 instances are launched from Amazon Machine Images (AMIs). A given public AMI:

  • A. Can only be used to launch EC2 instances in the same AWS availability zone as the AMI is stored
  • B. Can only be used to launch EC2 instances in the same country as the AMI is stored
  • C. Can only be used to launch EC2 instances in the same AWS region as the AMI is stored
  • D. Can be used to launch EC2 instances in any AWS region

C. AMIs are only available in the region they are created. Even in the case of the AWS-provided AMIs, AWS has actually copied the AMIs for you to different regions. You cannot access an AMI from one region in another region. However, you can copy an AMI from one region to another

Reference: https://aws.amazon.com/amazon-linux-ami/

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Q18: Which of the following statements is true about the Elastic File System (EFS)?

  • A. EFS can scale out to meet capacity requirements and scale back down when no longer needed
  • B. EFS can be used by multiple EC2 instances simultaneously
  • C. EFS cannot be used by an instance using EBS
  • D. EFS can be configured on an instance before launch just like an IAM role or EBS volumes

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A. and B.

Reference: https://aws.amazon.com/efs/

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Q19: IAM Policies, at a minimum, contain what elements?

  • A. ID
  • B. Effects
  • C. Resources
  • D. Sid
  • E. Principle
  • F. Actions

B. C. and F.

Effect – Use Allow or Deny to indicate whether the policy allows or denies access.

Resource – Specify a list of resources to which the actions apply.

Action – Include a list of actions that the policy allows or denies.

Id, Sid aren't required fields in IAM Policies. But they are optional fields

Reference: AWS IAM Access Policies

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Q20: What are the main benefits of IAM groups?

  • A. The ability to create custom permission policies.
  • B. Assigning IAM permission policies to more than one user at a time.
  • C. Easier user/policy management.
  • D. Allowing EC2 instances to gain access to S3.

B. and C.

A. is incorrect: This is a benefit of IAM generally or a benefit of IAM policies. But IAM groups don't create policies, they have policies attached to them.

Reference: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_groups.html

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Q21: What are benefits of using AWS STS?

  • A. Grant access to AWS resources without having to create an IAM identity for them
  • B. Since credentials are temporary, you don’t have to rotate or revoke them
  • C. Temporary security credentials can be extended indefinitely
  • D. Temporary security credentials can be restricted to a specific region

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Q22: What should the Developer enable on the DynamoDB table to optimize performance and minimize costs?

  • A. Amazon DynamoDB auto scaling
  • B. Amazon DynamoDB cross-region replication
  • C. Amazon DynamoDB Streams
  • D. Amazon DynamoDB Accelerator

D. DAX is a DynamoDB-compatible caching service that enables you to benefit from fast in-memory performance for demanding applications. DAX addresses three core scenarios:

  1. As an in-memory cache, DAX reduces the response times of eventually-consistent read workloads by an order of magnitude, from single-digit milliseconds to microseconds.
  2. DAX reduces operational and application complexity by providing a managed service that is API-compatible with Amazon DynamoDB, and thus requires only minimal functional changes to use with an existing application.
  3. For read-heavy or bursty workloads, DAX provides increased throughput and potential operational cost savings by reducing the need to over-provision read capacity units. This is especially beneficial for applications that require repeated reads for individual keys.

Reference: AWS DAX

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Q23: A Developer has been asked to create an AWS Elastic Beanstalk environment for a production web application which needs to handle thousands of requests. Currently the dev environment is running on a t1 micro instance. How can the Developer change the EC2 instance type to m4.large?

  • A. Use CloudFormation to migrate the Amazon EC2 instance type of the environment from t1 micro to m4.large.
  • B. Create a saved configuration file in Amazon S3 with the instance type as m4.large and use the same during environment creation.
  • C. Change the instance type to m4.large in the configuration details page of the Create New Environment page.
  • D. Change the instance type value for the environment to m4.large by using update autoscaling group CLI command.

B. The Elastic Beanstalk console and EB CLI set configuration options when you create an environment. You can also set configuration options in saved configurations and configuration files. If the same option is set in multiple locations, the value used is determined by the order of precedence.
Configuration option settings can be composed in text format and saved prior to environment creation, applied during environment creation using any supported client, and added, modified or removed after environment creation.
During environment creation, configuration options are applied from multiple sources with the following precedence, from highest to lowest:

  • Settings applied directly to the environment – Settings specified during a create environment or update environment operation on the Elastic Beanstalk API by any client, including the AWS Management Console, EB CLI, AWS CLI, and SDKs. The AWS Management Console and EB CLI also applyrecommended values for some options that apply at this level unless overridden.
  • Saved Configurations
    Settings for any options that are not applied directly to the
    environment are loaded from a saved configuration, if specified.
  • Configuration Files (.ebextensions)– Settings for any options that are not applied directly to the
    environment, and also not specified in a saved configuration, are loaded from configuration files in the .ebextensions folder at the root of the application source bundle.

    Configuration files are executed in alphabetical order. For example,.ebextensions/01run.configis executed before.ebextensions/02do.config.

  • Default Values– If a configuration option has a default value, it only applies when the option is not set at any of the above levels.

If the same configuration option is defined in more than one location, the setting with the highest precedence is applied. When a setting is applied from a saved configuration or settings applied directly to the environment, the setting is stored as part of the environment's configuration. These settings can be removed with the AWS CLI or with the EB CLI
.
Settings in configuration files are not applied
directly to the environment and cannot be removed without modifying the configuration files and deploying a new application version.
If a setting applied with one of the other methods is removed, the same setting will be loaded from configuration files in the source bundle.

Reference: Managing ec2 features – Elastic beanstalk

Q24: What statements are true about Availability Zones (AZs) and Regions?

  • A. There is only one AZ in each AWS Region
  • B. AZs are geographically separated inside a region to help protect against natural disasters affecting more than one at a time.
  • C. AZs can be moved between AWS Regions based on your needs
  • D. There are (almost always) two or more AZs in each AWS Region

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