AWS Developer Associate Practice Questions Part 3

Amazon SQS is engineered to provide “at least once” delivery of all messages in its queues. Although most of the time, each message will be delivered to your application exactly once, you should design your system so that processing a message more than once does not create any errors or inconsistencies.

The EC2 instances are registered with the load balancer using the IP addresses associated with the instances. When an instance is stopped and then started, the IP address associated with the instance changes. This prevents the load balancer from routing traffic to the restarted instance. When the user stops and then starts registered EC2 instances, it is recommended that to de-register the stopped instance from load balancer, and then register the restarted instance. Failure to do so may prevent the load balancer from performing health checks and routing the traffic to the restarted instance.

AWS CloudFormation allows you to create Microsoft Windows stacks based on Amazon EC2 Windows Amazon Machine Images (AMIs) and provides you with the ability to install software, to use remote desktop to access your stack, and to update and configure your stack.

In AWS CloudFormation, each AWS CloudFormation account is limited to a maximum of 20 stacks.

When a user creates an EBS volume and attaches it as a device, it is required to mount the device. If the device/volume is not mounted it will not be available in the listing.

In DynamoDB, Scan operations are always eventually consistent.

To send push notifications to mobile devices using Amazon SNS and ADM, you need to obtain the following: Registration ID and Client secret.

If the user is launching RDS with Multi AZ the user cannot provision the Availability Zone. RDS is launched automatically instead

In Amazon SWF, workflow execution time is up to maximum 1 year.

Amazon DynamoDB supports three scalar data types: Number, String, and Binary. Additionally, Amazon DynamoDB supports multi-valued types: Number Set, String Set, and Binary Set.

In AWS CloudFormation, the default value is overridden if you specify a value for the parameter as part of theaws cloudformation create-stack –parameters option. Parameter values you override at runtime are returned as part of the aws cloudformation describe-stacks command, unless you suppress that in the parameter declaration by including the NoEcho property with a value of true.

When creating an RDS instance, the user needs to specify whether it is Multi AZ or not. If the user does not provide the value for the zone, the maintenance window or automated backup window, RDS will automatically select the value.

AWS Elastic Beanstalk is best suited for those groups who want to deploy and manage their applications within minutes in the AWS cloud. As a bonus, you don’t even need experience with cloud computing to get started.

Amazon DynamoDB integrates with AWS Identity and Access Management (IAM). You can use AWS IAM to grant access to Amazon DynamoDB resources and API actions. To do this, you first write an AWS IAM policy, which is a document that explicitly lists the permissions you want to grant. You then attach that policy to an AWS IAM user or role.

A user can always create a new EBS volume of a higher size than the original snapshot size. The user cannot create a volume of a lower size. When the new volume is created the size in the instance will be shown as the original size. The user needs to change the size of the device with resize2fs or other OS specific commands.

In relation to Amazon Simple Workflow Service (Amazon SWF), an activity worker is a program that receives activity tasks, performs them, and provides results back. Which translates to a piece of software that implements tasks.

In DynamoDB, you will be charged for the storage and the throughput you use rather than for the I/O which has been used.

The ListTables operation requires no parameters. However, you can specify optional parameters. For example, you can set the limit parameter if you want to use paging to limit the number of table names per page.

Amazon SQS supports an unlimited number of queues and unlimited number of messages per queue for each user. Please be aware that Amazon SQS automatically deletes messages that have been in the queue for more than 4 days.

Speaking about DynamoDB, if your application performs more reads/second or writes/second than your table’s provisioned throughput capacity allows, requests above your provisioned capacity will be throttled and you will receive 400 error codes.

The Multi AZ feature allows the user to achieve High Availability. MS SQL does not support Multi AZ.

Newly created IAM users have no password and no access key (access key ID and secret access key). If the user needs to administer your AWS resources using the AWS Management Console, you can create a password for the user. If the user needs to interact with AWS programmatically (using the command line interface (CLI), the AWS SDK, or service-specific APIs), you can create an access key for that user. The credentials you create for users are what they use to uniquely identify themselves to AWS.

When you use the AWS Elastic Beanstalk console to deploy a new application or an application version, you’ll need to upload a source bundle.

Generally with IAM users, the password can be modified in two ways. The first option is to define the IAM level policy which allows each user to modify their own passwords. The other option is to create a group and create a policy for the group which can change the passwords of various IAM users.

Amazon S3 offers access policy options broadly categorized as resource-based policies and user policies. Access policies, such as ACL and resource policy can be attached to the bucket.  With the object the user can only have ACL and not an object policy. The user can also attach access policies to the IAM users in the account. These are called user policies.

Comparing with on-premises or EC2 based MS SQL, RDS provides an automated backup feature. PIOPS is available with both RDS and EBS. However, HA is not available with MS SQL.

A user can share an AMI with another user / peer using the command: ec2-modify-image-attribute <AMI-ID> -l -a <AWS Account ID>

Amazon Simple workflow Service (SWF) is a service aimed to provide support for complex distributed tasks with tight requirements regarding aspects like scalability, fault tolerance and resilience.

The current version of AWS Elastic Beanstalk uses the Amazon Linux AMI or the Windows Server 2008 R2 AMI.

Queue names are limited to 80 characters. Alphanumeric characters plus hyphens (-) and underscores (_) are allowed. Queue names must be unique within an AWS account. After you delete a queue, you can reuse the queue name.

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.

The AWS RDS DB instance is an isolated DB environment provided by AWS in which the user can create more than 1 database. The maximum size of the instance should be between 5 GB and 3 TB. The size of each DB can be anything in this range.

In DynamoDB, DescribeTable returns information about the table, including the current status of the table, when it was created, the primary key schema, and any indexes on the table.

To understand pricing in DynamoDB, consider the following example. If you create a table and request 10 units of write capacity and 200 units of read capacity of provisioned throughput, you would be charged: $0.01 + (4 x $0.01) = $0.05 per hour

In AWS Elastic Beanstalk, you can update your deployed application, even while it is part of a running environment. For a Java application, you can also use the AWS Toolkit for Eclipse to update your deployed application.

AWS reserve the right to delete a queue if none of the following requests have been issued against the queue for more than 30 consecutive days:

• SendMessage
• ReceiveMessage
• DeleteMessage
• GetQueueAttributes
• SetQueueAttributes

You should design your application with this in mind.

AWS Elastic Beanstalk is an easy way for you to quickly deploy and manage applications in the AWS cloud. You simply upload your application, and Elastic Beanstalk automatically handles the deployment details of capacity provisioning, load balancing, auto-scaling, and application health monitoring.

While launching an EC2 instance, the user can create a new key pair, select an existing key pair or proceed without a key pair. The user cannot upload a new key pair in the EC2 instance launch console.

AWS CloudFormation can be used to bootstrap both the Chef Server and Chef Client software on your EC2 instances.

The fundamental concept in Amazon SWF is the workflow. A workflow is a set of activities that carry out some objective, together with logic that coordinates the activities.

Elastic Beanstalk leverages AWS services such as Amazon Elastic Cloud Compute (Amazon EC2), Amazon Simple Storage Service (Amazon S3), Amazon Simple Notification Service (Amazon SNS), Elastic Load Balancing and Auto Scaling to deliver the same highly reliable, scalable, and cost-effective infrastructure that hundreds of thousands of businesses depend on today.

In DynamoDB, DeleteItem deletes a single item in a table by primary key, but BatchDeleteItem doesn’t exist.

If an EBS volume is attached to a running EC2 instance, the user needs to detach the volume from the original instance and then attach it to a new running instance. The user doesn’t need to stop / terminate the original instance.

When you load your table directly from an Amazon DynamoDB table, you have the option to control the amount of Amazon DynamoDB provisioned throughput you consume.

AWS RDS is a managed database server offered by AWS, which makes it easy to set up, operate, and scale a relational database or structured data in cloud.

The IAM policy allows to test a user in the account 12112112 to perform:

• s3:GetBucketLocation
• s3:ListBucket
• s3:GetObject

Amazon S3 permissions on the test bucket.

When you use the AWS Elastic Beanstalk console to deploy a new application or an application version, you’ll need to upload a source bundle. Your source bundle must meet the following requirements:

• Consist of a single .zip file or .war file
• Not exceed 512 MB
• Not include a parent folder or top-level directory (subdirectories are fine)

Amazon DynamoDB supports the following data types:

• Scalar data types (like Number, String, and Binary)
• Multi-valued types (like String Set, Number Set, and Binary Set).

In AWS CloudFormation, Amazon EC2 resources that support the tagging feature can also be tagged in an AWS template. The tag values can refer to template parameters, other resource names, resource attribute values (e.g. addresses), or values computed by simple functions (e.g., a concatenated list of strings).

With regard to IAM, when a request is made, the AWS service decides whether a given request should be allowed or denied. The evaluation logic follows these rules:

• By default, all requests are denied. (In general, requests made using the account credentials for resources in the account are always allowed.)
• An explicit allow policy overrides this default.
• An explicit deny policy overrides any allows.

The EBS snapshots are a point in time backup of the EBS volume. It is an incremental snapshot, but is always specific to the region and never specific to a single AZ.
Hence the statement “It is stored in the same AZ as the volume” is incorrect.

An ELB performs a health check on its instances to ensure that it diverts traffic only to healthy instances. The ELB can perform a health check on HTTP, HTTPS, TCP and SSL protocols.

DynamoDB is a fast, fully managed NoSQL database service.

In DynamoDB, a secondary index is a data structure that contains a subset of attributes from a table, along with an alternate key to support Query operations.

Maximum number of AWS CloudFormation stacks that you can create is 20 stacks.

Before Auto Scaling selects an instance to terminate, it first identifies the Availability Zone that has more instances than the other Availability Zones used by the group. If all the Availability Zones have the same number of instances, it identifies a random Availability Zone.