Answers to Assessment Test
- D. Auto Scaling may cause you to reach limits of other services, such as the default number of Amazon EC2 instances you can currently launch within a region, which is 20.
- B. The Elastic Load Balancing service allows you to distribute traffic across a group of Amazon Elastic Compute Cloud (Amazon EC2) instances in one or more Availability Zones within a region.
- A and B. Amazon CloudWatch has two plans: basic and detailed. There are no diagnostic, precognitive, or retroactive monitoring plans for Amazon CloudWatch.
- B, C, and E. You must do the following to create a public subnet with Internet access:
Attach an IGW to your Amazon VPC.
Create a subnet route table rule to send all non-local traffic (for example, 0.0.0.0/0) to the IGW.
Configure your network ACLs and security group rules to allow relevant traffic to flow to and from your instance.
You must do the following to enable an Amazon EC2 instance to send and receive traffic from the Internet:
Assign a public IP address or EIP address.
- A, D, and E. If a security group is not specified at launch, then an Amazon EC2 instance will be launched into the default security group for the Amazon VPC. The default security group allows communication between all resources within the security group, allows all outbound traffic, and denies all other traffic.
- B and D. To protect data in transit from the clients to the web application, HTTPS with server certificate authentication should be used. To protect data in transit from the web application to the database, SSL/TLS for database connection should be used.
- A. Don't create an IAM user (or an IAM group) and pass the user's credentials to the application or embed the credentials in the application. Instead, create an IAM role that you attach to the Amazon EC2 instance to give applications running on the instance temporary security credentials. The credentials have the permissions specified in the policies attached to the role. A directory is not an identity object in IAM.
- B, C, and D. When a request is made, the AWS service decides whether a given request should be allowed or denied. The evaluation logic follows these rules:
1) By default, all requests are denied (in general, requests made using the account credentials for resources in the account are always allowed).
2) An explicit allow overrides this default.
3) An explicit deny overrides any allows.
- A. Amazon EMR uses Apache Hadoop as its distributed data processing engine. Hadoop is an open source, Java software framework that supports data-intensive distributed applications running on large clusters of commodity hardware. Hive, Pig, and HBase are packages that run on top of Hadoop.
- B. An environment tier whose web application runs background jobs is known as a worker tier. An environment tier whose web application processes web requests is known as a web server tier. Database and batch are not valid environment tiers.
- D. Multi-AZ deployment uses synchronous replication to a different Availability Zone so that operations can continue on the replica if the master database stops responding for any reason. Automated backups provide disaster recovery, not high availability. Security groups, while important, have no effect on availability. Maintenance windows are actually times when the database may not be available.
- A, B, and D. Amazon RDS will launch Amazon Elastic Compute Cloud (Amazon EC2) instances, install the database software, handle all patching, and perform regular backups. Anything within the database software (schema, user accounts, and so on) is the responsibility of the customer.
- A. Amazon Redshift is a petabyte-scale data warehouse. It is not well suited for unstructured NoSQL data or highly dynamic transactional data. It is in no way a cache.
- D. There can be one secondary index per table, and it must be created when the table is created.
- B. The Amazon Kinesis family of services provides functionality to ingest large streams of data. Amazon Kinesis Firehose is specifically designed to ingest a stream and save it to any of the three storage services listed in Response B.
- B. Amazon S3 and Amazon Glacier are the most cost-effective storage services. After a year, when the objects are unlikely to be accessed, you can save costs by transferring the objects to Amazon Glacier where the retrieval time is three to five hours.
- D. Server access logs provide a record of any access to an object in Amazon S3.
- C. Amazon S3 provides read-after-write consistency for PUTs to new objects (new key), but eventual consistency for GETs and DELETEs of existing objects (existing key). Response C changes the existing object so that a subsequent GET may fetch the previous and inconsistent object.
- B. AWS will never transfer data between regions unless directed to by you. Durability in Amazon S3 is achieved by replicating your data geographically to different Availability Zones regardless of the versioning configuration. AWS doesn't use tapes.
- C. Amazon CloudFront provides the best user experience by delivering the data from a geographically advantageous edge location. Signed URLs allow you to control access to authenticated users.
- A, B, and D. In the AWS shared responsibility model, customers retain control of what security they choose to implement to protect their own content, platform, applications, systems, and networks, no differently than they would for applications in an on-site data center.
- B. An activity worker is a process or thread that performs the activity tasks that are part of your workflow. Each activity worker polls Amazon SWF for new tasks that are appropriate for that activity worker to perform; certain tasks can be performed only by certain activity workers. After receiving a task, the activity worker processes the task to completion and then reports to Amazon SWF that the task was completed and provides the result. The activity task represents one of the tasks that you identified in your application.
- B. In an Amazon VPC, an instance's Elastic IP address remains associated with an instance when the instance is stopped.
- C. You pay a set hourly price for an On Demand instance from when you launch it until you explicitly stop or terminate it. Spot instances can be terminated when the spot price goes above your bid price. Reserved instances involve paying for an instance over a one- or three-year term. Dedicated instances run on hardware dedicated to your account and are not a pricing model.
- D. The data in an instance store persists only during the lifetime of its associated instance. If an instance is stopped or terminated, then the instance store does not persist. Rebooting an instance does not shut down the instance; if an instance reboots (intentionally or unintentionally), data on the instance store persists. Security groups have nothing to do with the lifetime of an instance and have no effect here.
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