AWS Developer Associate Practice Questions Part 2

In DynamoDB, SSDs help achieve design goals of predictable low-latency response times for storing and accessing data at any scale. The high I/O performance of SSDs also enables to serve high-scale request workloads cost efficiently, and to pass this efficiency along in low request pricing.

Amazon Simple Queue Service (SQS) is a fast, reliable, scalable, and fully managed message queuing service. SQS provides a simple and cost-effective way to decouple the components of an application. In this case, the user can use AWS SQS to send messages which are received from an application and sent to DB. The application can continue processing data without waiting for any acknowledgement from DB. The user can use SQS to transmit any volume of data without losing messages or requiring other services to always be available.

When a user is trying to create a policy from the AWS console, it will have options such as create policy from templates or use a policy generator. The user can also define a custom policy or chose the option to have no permission. The policy simulator is not available in the console.

Global secondary index — an index with a hash and range key that can be different from those on the table.

AWS S3 follows the eventual consistent model in the US Standard Region. Once the object is updated it may return the new value or the old value based on whether all the content is replicated across multiple servers until it becomes consistent (eventual).

By default, SQS queues allow you to send the largest supported payload size, currently 256KB. You can choose to specify a limit on how many bytes can be sent per payload, using the MaximumMessageSize attribute of the SetQueueAttributes method.

If a user is configuring HTTPS on the front end and TCP on the back end, ELB will not allow saving these listeners and will respond with the message.

“Load Balancer protocol is an application layer protocol, but instance protocol is not. Both the Load Balancer protocol and the instance protocol should be at the same layer. Please fix.”

When you create a table with a hash-and-range key in DynamoDB, you can also define one or more secondary indexes on that table.

The data model of DynamoDB is:

• “Table”, a collection of Items;
• “Items”, with Keys and one or more Attribute;
• “Attribute”, with Name and Value.

The Manual Scaling as part of Auto Scaling allows the user to change the capacity of Auto Scaling group. The user can add / remove EC2 instances on the fly. To execute manual scaling, the user should modify the desired capacity. AutoScaling will adjust instances as per the requirements. If the user is trying to CLI, he can use command

as-set-desired-capacity <Auto Scaling Group Name> --desired-capacity <New Capacity>

RDS DB instance storage comes in two types: standard and provisioned IOPS. Standard storage is allocated on the Amazon EBS volumes and connected to the user’s DB instance. Provisioned IOPS uses optimized EBS volumes and an optimized configuration stack. It provides additional, dedicated capacity for the EBS I/O.

When a user is trying to detach an EBS volume, the user can either terminate the instance or explicitly remove the volume. It is a recommended practice to unmount the volume first to avoid any file system damage.

When the user makes any changes to the RDS security group the rule status will be authorizing for some time until the changes are applied to all instances that the group is connected with. Once the changes are propagated the rule status will change to authorized.

SQS allows the user to move data between distributed components of applications so they can perform different tasks without losing messages or requiring each component to be always available. The user can delete a queue at any time, whether it is empty or not.  It is important to note that queues retain messages for a set period of time. By default, a queue retains messages for four days.

If an organization has created the IAM users, the users can access AWS services either with an IAM specific login/password or console. The organization can generate the IAM X.509 certificates to access AWS with CLI. The organization can also enable MFA for each IAM user, which allows an added security for each IAM user. If the organization has created the access key and secret key than the user cannot access the console using those keys. Access key and secret access key are useful for CLI or Webservices.

Amazon DynamoDB and Amazon CloudWatch are integrated, so you can gather and analyze performance metrics. You can monitor these metrics using the CloudWatch console, CloudWatch’s own command-line interface, or programmatically using the CloudWatch API.

The user can configure the AutoScaling group to automatically scale up and then scale down based on the specified conditions. To configure this, the user must setup policies which will get triggered by the CloudWatch alarms.

Amazon Relational Database Service (Amazon RDS) is a web service that makes it easier to set up, operate, and scale a relational database in the cloud. AWS RDS supports popular DBs, such as MySQL, PostgreSQL, MS SQL and Oracle. This means that the code, applications, and tools user is already using with existing databases can be used with Amazon RDS too. In short, it is a managed Relation Database offering from AWS which manages backups, software patching, automatic failure detection, and recovery of Database.

Amazon RDS provides two different methods for backing up and restoring the Amazon DB instances. A brief I/O freeze, typically lasting a few seconds, occurs during both automated backups and DB snapshot operations on Single-AZ DB instances.

In Amazon SWF, a task represents a logical unit of work that is performed by a component of your application. When using Amazon SWF, you implement workers to perform tasks.

AutoScaling attempts to distribute instances evenly between the Availability Zones that are enabled for the user’s AutoScaling group. Auto Scaling does this by attempting to launch new instances in the Availability Zone with the fewest instances.

In Amazon SNS, besides pushing cloud notifications directly to mobile devices, Amazon SNS can also deliver notifications by SMS text message or email, to Amazon Simple Queue Service (SQS) queues, or to any HTTP endpoint.

An EBS volume provides persistent data storage. The user can attach a volume to any instance provided they are both in the same AZ. Even if they are in the same region but in a different AZ, it will not be able to attach the volume to that instance.

RDS charges the user on a pay as you go basis. It charges the user based on the instance type, number of hours that the instance is running, data transfer, storage cost as well for the I/O requests. The monitoring is free of cost.

AWS Elastic Beanstalk can use the Amazon Simple Notification Service (Amazon SNS) to notify you of important events affecting your application.

It is a recommended approach to avoid using the access and secret access keys of the root account. Thus, do not download or delete it. Instead make the IAM user as powerful as the root account and use its credentials. The user cannot generate their own access and secret access keys as they are always generated by AWS.

Amazon DynamoDB supports increment or decrement atomic operations.

In AWS Elastic Beanstalk, applications can have many versions and each application version is unique. In a running environment, you can deploy any application version you already uploaded to the application or you can upload and immediately deploy a new application version. You might upload multiple application versions to test differences between one version of your web application and another.

When an organization is using AWS IAM for creating various users and manage their access rights, the IAM user can not use the login URL http://aws.amazon.com/console to access AWS management console. The console login URL for the IAM user will have AWS account ID of that organization to identify the IAM user belongs to particular account. The AWS console login URL for the IAM user will be https:// <AWS_Account_ID>.signin.aws.amazon.com/console/. In this case it will be https:// 111122223333.signin.aws.amazon.com/console/

In Amazon SNS, when you want to write a policy, each policy is a JSON document.

The template is a JSON-format, text-based file that describes all the AWS resources you need to deploy to run your application.

If a user wants the URL of the AWS IAM sign-in page to have a company name instead of the AWS account ID, he can create an alias for his AWS account ID. The alias should be unique.

If the user needs to connect to RDS then he has to open port 3306 in the RDS security group for his IP address.

If the user is using the server-side encryption feature, Amazon S3 encrypts the object data before saving it on disks in its data centres and decrypts it when the user downloads the objects. Thus, the user is free from the tasks of managing encryption, encryption keys, and related tools.

While AWS Elastic Beanstalk creates your AWS resources and launches your application, the environment will be in a Launching (gray) state. Status messages about launch events are displayed in the environment’s dashboard. If the environment health is gray, the environment is still in the process of being launched.

Identity federation enables users from an existing directory to access resources within your AWS account, making it easier to manage your users by maintaining their identities in a single place. In this case, the federated user is the only solution since AWS does not allow creating more than 5000 IAM users.

Amazon RDS provides two different methods for backing up and restoring the Amazon DB instances: automated backups and DB snapshots. Automated backups automatically back up the DB instance during a specific, user-definable backup window, and keep the backups for a limited, user-specified period of time.

In Amazon SWF, an activity worker is a program that receives activity tasks, performs them, and provides results back. Note that the task itself might actually be performed by a person, in which case the person would use the activity worker software for the receipt and disposition of the task. An example might be a statistical analyst, who receives sets of data, analyzes them, and then sends back the analysis.

The key to manage the sticky session is determining how long the load balancer should route the user’s request to the same application instance. If the application has its own session cookie, then the user can set the Elastic Load Balancing to create the session cookie to follow the duration specified by the application’s session cookie. If the user’s application does not have its own session cookie, then he can set the Elastic Load Balancing to create a session cookie by specifying his own stickiness duration.

If a user wants the URL of the AWS IAM sign-in page to have the company name instead of the AWS account ID, he can create an alias for his AWS account ID. The alias must be unique across all Amazon Webservices products and contain only digits, lowercase letters, and hyphens.

In Amazon SNS, It costs $1.00 to send one million mobile push notifications ($0.50 per million publishes, plus $0.50 per million mobile push notification deliveries).

If a user has launched an EBS backed instance, the user will be charged for the EBS volume even though the instance is in a stopped state. The instance will be charged for the EC2 hourly cost only when it is running.

Amazon SNS makes it simple and cost-effective to push to mobile devices, such as iPhone, iPad, Android, Kindle Fire, and internet connected smart devices, as well as pushing to other distributed services. In this case, the user can configure that Cloudwatch sends an alarm on when the threshold is crossed to SNS which will trigger an SMS.

It is a recommended rule that the root user should grant the least privileges to the IAM user or the group. The higher the privileges, the more problems it can create.

The SQS message retention period is configurable and can be set anywhere from 1 minute to 2 weeks. The default is 4 days and once the message retention limit is reached your messages will be automatically deleted. The option for longer message retention provides greater flexibility to allow for longer intervals between message production and consumption.

In Amazon SWF, the maximum open activity tasks is up to 1,000 per workflow execution.

Yes, it is possible to have one instance part of two separate ELBs, though both ELBs have different configurations. ELBs are never launched in specific zones.

AWS RDS provides a managed DB platform, which offers features, such as automated backup, patch management, automated failure detection and recovery. The scaling is not automated and the user needs to plan it with a few clicks.

If a user wants the URL of the AWS IAM sign-in page to have a company name instead of the AWS account ID, he can create an alias for his AWS account ID.

In Amazon SWF, the coordination logic in a workflow is contained in a software program called a decider. The decider schedules activity tasks, provides input data to the activity workers, processes events that arrive while the workflow is in progress, and ultimately ends (or closes) the workflow when the objective has been completed.

AWS RRS provides the same functionality as AWS S3, but at a cheaper rate. It is ideally suited for non mission critical applications. It provides less durability than S3, but is a cheaper option.

To update an existing stack, you must submit a template that specifies updates for the properties of resources in the stack. This can be done by using the AWS CloudFormation console, the aws cloudformation update-stack CLI command, or with the UpdateStack API.

The user cannot authorize an Amazon EC2 security group if it is in a different AWS Region than the RDS DB instance. The user can authorize an IP range or specify an Amazon EC2 security group in the same region that refers to an IP address in another region.

Amazon Simple Queue Service (SQS) is a fast, reliable, scalable, and fully managed message queuing service. SQS provides a simple and cost-effective way to decouple the components of an application. The user can configure SQS, which will decouple the call between the EC2 application and S3. Thus, the application does not keep waiting for S3 to provide the data.

AWS Elastic Beanstalk will change the health status of a web server environment tier to gray color when your application’s health status is unknown (because status is reported when the application is not in the ready state).

An IAM group is a collection of IAM users. Groups let the user specify permissions for a collection of users, which can make it easier to manage the permissions for those users.

AWS Elastic Load Balancing continuously checks the health of an instance. If one of the instances is unhealthy it stops sending traffic to it and automatically reroutes the traffic to the remaining running EC2 instances. If the failed EC2 instance is restored, Elastic Load Balancing will again start sending traffic to that instance.

Amazon RDS provides two different methods for backing up and restoring the Amazon DB instances: automated backups and DB snapshots. Automated backups automatically back up the DB instance during a specific, user-definable backup window, and keep the backups for a limited, user-specified period of time. The maximum period can be 35 days.

In general in DynamoDB, decreases in throughput will take anywhere from a few seconds to a few minutes, while increases in throughput will typically take anywhere from a few minutes to a few hours.