AWS-Certified-DevOps-Engineer-Professional | Top Tips Of Most Recent AWS-Certified-DevOps-Engineer-Professional Practice Test

NEW QUESTION 1
You run a clustered NoSQL database on AWS EC2 using AWS EBS. You need to reduce latency for database response times. Performance is the most important concern, not availability. You did not perform the initial setup, someone without much AWS knowledge did, so you are not sure if they configured everything optimally. Which of the following is NOT likely to be an issue contributing to increased latency?

• A. The EC2 instances are not EBS Optimized.
• B. The database and requesting system are both in the wrong Availability Zone.
• C. The EBS Volumes are not using PIOPS.
• D. The database is not running in a placement grou

Answer: B

Explanation:
For the highest possible performance, all instances in a clustered database like this one should be in a single Availability Zone in a placement group, using EBS optimized instances, and using PIOPS SSD EBS Volumes. The particular Availability Zone the system is running in should not be important, as long as it is the same as the requesting resources.
Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html

NEW QUESTION 2
There is a very serious outage at AWS. EC2 is not affected, but your EC2 instance deployment scripts stopped working in the region with the outage. What might be the issue?

• A. The AWS Console is down, so your CLI commands do not work.
• B. S3 is unavailable, so you can't create EBS volumes from a snapshot you use to deploy new volumes.
• C. AWS turns off the <code>DepIoyCode</code> API call when there are major outages, to protect from system floods.
• D. None of the other answers make sens
• E. If EC2 is not affected, it must be some other issu

Answer: B

Explanation:
S3 stores all snapshots. If S3 is unavailable, snapshots are unavailable.
Amazon EC2 also uses Amazon S3 to store snapshots (backup copies) of the data volumes. You can use snapshots for recovering data quickly and reliably in case of application or system failures. You can also use snapshots as a baseline to create multiple new data volumes, expand the size of an existing data volume, or move data volumes across multiple Availability Zones, thereby making your data usage highly scalable. For more information about using data volumes and snapshots, see Amazon Elastic Block Store.
Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AmazonS3.htmI

NEW QUESTION 3
What does it mean if you have zero IOPS and a non-empty I/O queue for all EBS volumes attached to a running EC2 instance?

• A. The I/O queue is buffer flushing.
• B. Your EBS disk head(s) is/are seeking magnetic stripes.
• C. The EBS volume is unavailable.
• D. You need to re-mount the EBS volume in the O

Answer: C

Explanation:
This is the definition of Unavailable from the EC2 and EBS SLA.
"UnavaiIabIe" and "Unavai|abi|ity" mean... For Amazon EBS, when all of your attached volumes perform zero read write IO, with pending IO in the queue.
Reference: https://aws.amazon.com/ec2/s|a/

NEW QUESTION 4
You need to run a very large batch data processing job one time per day. The source data exists entirely in S3, and the output of the processing job should also be written to S3 when finished. If you need to version control this processing job and all setup and teardown logic for the system, what approach should you use?

• A. Model an AWS EMR job in AWS Elastic Beanstalk.
• B. Model an AWS EMR job in AWS CloudFormation.
• C. Model an AWS EMR job in AWS OpsWorks.
• D. Model an AWS EMR job in AWS CLI Compose

Answer: B

Explanation:
To declaratively model build and destroy of a cluster, you need to use AWS CIoudFormation. OpsWorks and Elastic Beanstalk cannot directly model EMR Clusters. The CLI is not declarative, and CLI Composer does not exist.
Reference:
http://docs.aws.amazon.com/AWSCIoudFormation/latest/UserGuide/aws-resource-emr-cluster.html

NEW QUESTION 5
Your CTO thinks your AWS account was hacked. What is the only way to know for certain if there was unauthorized access and what they did, assuming your hackers are very sophisticated AWS engineers and doing everything they can to cover their tracks?

• A. Use CloudTrai| Log File Integrity Validation.
• B. Use AWS Config SNS Subscriptions and process events in real time.
• C. Use CIoudTraiI backed up to AWS S3 and Glacier.
• D. Use AWS Config Timeline forensic

Answer: A

Explanation:
You must use CloudTraiI Log File Validation (default or custom implementation), as any other tracking method is subject to forgery in the event of a full account compromise by sophisticated enough hackers. Validated log files are invaluable in security and forensic investigations. For example, a validated log file enables you to assert positively that the log file itself has not changed, or that particular user credentials performed specific API actMty. The CIoudTraiI log file integrity validation process also lets you know if a log file has been deleted or changed, or assert positively that no log files were delivered to your account during a given period of time.
Reference:
http://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-log-fiIe-validation-intro.html

NEW QUESTION 6
You run operations for a company that processes digital wallet payments at a very high volume. One second of downtime, during which you drop payments or are otherwise unavailable, loses you on average USD 100. You balance the financials of the transaction system once per day. Which database setup is best suited to address this business risk?

• A. A multi-AZ RDS deployment with synchronous replication to multiple standbys and read-replicas for fast failover and ACID properties.
• B. A multi-region, multi-master, active-active RDS configuration using database-level ACID design principles with database trigger writes for replication.
• C. A multi-region, multi-master, active-active DynamoDB configuration using application control-level BASE design principles with change-stream write queue buffers for replication.
• D. A multi-AZ DynamoDB setup with changes streamed to S3 via AWS Kinesis, for highly durable storage and BASE properties.

Answer: C

Explanation:
Only the multi-master, multi-region DynamoDB answer makes sense. IV|u|ti-AZ deployments do not provide sufficient availability when a business loses USD 360,000 per hour of unavailability. As RDS does not natively support multi-region, and ACID does not perform well/at all over large distances between
regions, only the DynamoDB answer works. Reference:
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.CrossRegionRepI.htmI

NEW QUESTION 7
What is server immutability?

• A. Not updating a server after creation.
• B. The ability to change server counts.
• C. Updating a server after creation.
• D. The inability to change server count

Answer: A

Explanation:
disposable upgrades offer a simpler way to know if your application has unknown dependencies. The underlying EC2 instance usage is considered temporary or ephemeral in nature for the period of deployment until the current release is active. During the new release, a new set of EC2 instances are rolled out by terminating older instances. This type of upgrade technique is more common in an immutable infrastructure.
Reference: https://d0.awsstatic.com/whitepapers/overview-of-deployment-options-on-aws.pdf

NEW QUESTION 8
You have an asynchronous processing application using an Auto Scaling Group and an SQS Queue. The Auto Scaling Group scales according to the depth of the job queue. The completion velocity of the jobs has gone down, the Auto Scaling Group size has maxed out, but the inbound job velocity did not increase. What is a possible issue?

• A. Some of the newjobs coming in are malformed and unprocessable.
• B. The routing tables changed and none of the workers can process events anymore.
• C. Someone changed the IAM Role Policy on the instances in the worker group and broke permissions to access the queue.
• D. The scaling metric is not functioning correctl

Answer: A

Explanation:
The IAM Role must be fine, as if it were broken, NO jobs would be processed since the system would never be able to get any queue messages. The same reasoning applies to the routing table change. The scaling metric is fine, as instance count increased when the queue depth increased due to more messages entering than exiting. Thus, the only reasonable option is that some of the recent messages must be malformed and unprocessable.
Reference:
https://github.com/andrew-templeton/cloudacademy/blob/fca920b45234bbe99cc0e8efb9c65134884dd48 9/questions/null

NEW QUESTION 9
What is the scope of an EC2 security group?

• A. Availability Zone
• B. Placement Group
• C. Region
• D. VPC

Answer: C

Explanation:
A security group is tied to a region and can be assigned only to instances in the same region. You can't enable an instance to communicate with an instance outside its region using security group rules. Traffic
from an instance in another region is seen as WAN bandwidth.
Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/resources.htmI

NEW QUESTION 10
Your application consists of 10% writes and 90% reads. You currently service all requests through a Route53 Alias Record directed towards an AWS ELB, which sits in front of an EC2 Auto Scaling Group. Your system is getting very expensive when there are large traffic spikes during certain news events, during which many more people request to read similar data all at the same time. What is the simplest and cheapest way to reduce costs and scale with spikes like this?

• A. Create an S3 bucket and asynchronously replicate common requests responses into S3 object
• B. When a request comes in for a precomputed response, redirect to AWS S3.
• C. Create another ELB and Auto Scaling Group layer mounted on top of the other system, adding a tier to the syste
• D. Serve most read requests out of the top layer.
• E. Create a CloudFront Distribution and direct Route53 to the Distributio
• F. Use the ELB as an Origin and specify Cache Behaviours to proxy cache requests which can be served late.
• G. Create a Memcached cluster in AWS EIastiCach
• H. Create cache logic to serve requests which can be served late from the in-memory cache for increased performance.

Answer: C

Explanation:
CIoudFront is ideal for scenarios in which entire requests can be served out of a cache and usage patterns involve heavy reads and spikiness in demand.
A cache behavior is the set of rules you configure for a given URL pattern based on file extensions, file names, or any portion of a URL path on your website (e.g., *.jpg). You can configure multiple cache behaviors for your web distribution. Amazon CIoudFront will match incoming viewer requests with your list of URL patterns, and if there is a match, the service will honor the cache behavior you configure for that URL pattern. Each cache behavior can include the following Amazon CIoudFront configuration values: origin server name, viewer connection protocol, minimum expiration period, query string parameters, cookies, and trusted signers for private content.
Reference: https://aws.amazon.com/Cloudfront/dynamic-content/

NEW QUESTION 11
You are creating a new API for video game scores. Reads are 100 times more common than writes, and the top 1% of scores are read 100 times more frequently than the rest of the scores. What's the best design for this system, using DynamoDB?

• A. DynamoDB table with 100x higher read than write throughput, with CloudFront caching.
• B. DynamoDB table with roughly equal read and write throughput, with CloudFront caching.
• C. DynamoDB table with 100x higher read than write throughput, with E|astiCache caching.
• D. DynamoDB table with roughly equal read and write throughput, with EIastiCache cachin

Answer: D

Explanation:
Because the 100x read ratio is mostly driven by a small subset, with caching, only a roughly equal number of reads to writes will miss the cache, since the supermajority will hit the top 1% scores. Knowing we need to set the values roughly equal when using caching, we select AWS EIastiCache, because CIoudFront cannot directly cache DynamoDB queries, and EIastiCache is an excellent in-memory cache for database queries, rather than a distributed proxy cache for content delivery.
One solution would be to cache these reads at the application layer. Caching is a technique that is used in many high-throughput applications, offloading read actMty on hot items to the cache rather than to the database. Your application can cache the most popular items in memory, or use a product such as EIastiCache to do the same.
Reference: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GuideIinesForTabIes.htmI#GuideIi nesForTabIes.CachePopuIarItem

NEW QUESTION 12
Your company needs to automate 3 layers of a large cloud deployment. You want to be able to track this depIoyment's evolution as it changes over time, and carefully control any alterations. What is a good way to automate a stack to meet these requirements?

• A. Use OpsWorks Stacks with three layers to model the layering in your stack.
• B. Use CloudFormation Nested Stack Templates, with three child stacks to represent the three logicallayers of your cloud.
• C. Use AWS Config to declare a configuration set that AWS should roll out to your cloud.
• D. Use Elastic Beanstalk Linked Applications, passing the important DNS entires between layers using the metadata interface.

Answer: B

Explanation:
Only CIoudFormation allows source controlled, declarative templates as the basis for stack automation. Nested Stacks help achieve clean separation of layers while simultaneously providing a method to control all layers at once when needed.
Reference:
https://bIogs.aws.amazon.com/application-management/post/TxlT9JYOOS8AB9I/Use-Nested-Stacks-to- Create-Reusable-Templates-and-Support-Role-SpeciaIization

NEW QUESTION 13
You are designing a system which needs, at minimum, 8 m4.Iarge instances operating to service traffic. When designing a system for high availability in the us-east-1 region, which has 6 Availability Zones, you company needs to be able to handle death of a full availability zone. How should you distribute the
servers, to save as much cost as possible, assuming all of the EC2 nodes are properly linked to an ELB? Your VPC account can utilize us-east-1's AZ's a through f, inclusive.

• A. 3 servers in each of AZ's a through d, inclusive.
• B. 8 servers in each of AZ's a and b.
• C. 2 servers in each of AZ's a through e, inclusive.
• D. 4 servers in each of AZ's a through c, inclusiv

Answer: C

Explanation:
You need to design for N+1 redundancy on Availability Zones. ZONE_COUNT = (REQUIRED_INSTANCES / INSTANCE_COUNT_PER_ZONE) + 1. To minimize cost, spread the instances across as many possible zones as you can. By using a though e, you are allocating 5 zones. Using 2 instances, you have 10 total instances. If a single zone fails, you have 4 zones left, with 2 instances each, for a total of 8 instances. By spreading out as much as possible, you have increased cost by only 25% and significantly de-risked an availability zone failure.
Reference:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.htmI#concepts- regions-availability-zones

NEW QUESTION 14
For AWS CloudFormation, which is true?

• A. Custom resources using SNS have a default timeout of 3 minutes.
• B. Custom resources using SNS do not need a <code>ServiceToken</code> property.
• C. Custom resources using Lambda and <code>Code.ZipFiIe</code> allow inline nodejs resource composition.
• D. Custom resources using Lambda do not need a <code>ServiceToken</code>property

Answer: C

Explanation:
Code is a property of the AWS::Lambda::Function resource that enables to you specify the source code of an AWS Lambda (Lambda) function. You can point to a file in an Amazon Simple Storage Service (Amazon S3) bucket or specify your source code as inline text (for nodejs runtime environments only). Reference:
http://docs.aws.amazon.com/AWSCIoudFormation/latest/UserGuide/template-custom-resources.html

NEW QUESTION 15
Which of the following tools does not directly support AWS OpsWorks, for monitoring your stacks?

• A. AWS Config
• B. Amazon CIoudWatch Nletrics
• C. AWS CloudTraiI
• D. Amazon CIoudWatch Logs

Answer: A

Explanation:
You can monitor your stacks in the following ways: AWS OpsWorks uses Amazon CIoudWatch to provide thirteen custom metrics with detailed monitoring for each instance in the stack; AWS OpsWorks integrates with AWS CIoudTraiI to log every AWS OpsWorks API call and store the data in an Amazon S3 bucket; You can use Amazon CIoudWatch Logs to monitor your stack's system, application, and custom logs. Reference: http://docs.aws.amazon.com/opsworks/latest/userguide/monitoring.htmI

NEW QUESTION 16
You need to migrate 10 million records in one hour into DynamoDB. All records are 1.5KB in size. The data is evenly distributed across the partition key. How many write capacity units should you provision during this batch load?

• A. 6667
• B. 4166
• C. 5556
• D. 2778

Answer: C

Explanation:
You need 2 units to make a 1.5KB write, since you round up. You need 20 million total units to perform this load. You have 3600 seconds to do so. DMde and round up for 5556.
Reference: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ProvisionedThroughp ut.htmI

NEW QUESTION 17
When thinking of AWS OpsWorks, which of the following is not an instance type you can allocate in a stack layer?

• A. 24/7 instances
• B. Spot instances
• C. Time-based instances
• D. Load-based instances

Answer: B

Explanation:
AWS OpsWorks supports the following instance types, which are characterized by how they are started and stopped. 24/7 instances are started manually and run until you stop them.Time-based instances are run by AWS OpsWorks on a specified daily and weekly schedule. They allow your stack to automatically adjust the number of instances to accommodate predictable usage patterns. Load-based instances are automatically started and stopped by AWS OpsWorks, based on specified load metrics, such as CPU utilization. They allow your stack to automatically adjust the number of instances to accommodate variations in incoming traffic. Load-based instances are available only for Linux-based stacks. Reference: http://docs.aws.amazon.com/opsworks/latest/userguide/weIcome.htmI

NEW QUESTION 18
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