Ch4 Flashcards
- Which of the following are valid payment options for reserved instances? (Choose two.)
Actual usage pricing
Predictive pricing
All up-front pricing
Nothing up-front pricing
C, D. Reserved instances can be paid for in no up-front, partial up-front, and all up-front models, where all up-front is the least expensive and no up-front is the most expensive.
- Which of the following are not reasons to select an on-demand instance? (Choose two.)
Applications with short-term, spiky workloads
Applications that have flexible start and end times
Applications with steady-state usage
Applications being developed or tested on EC2 for the first time
B, C. Applications with spiky workloads are reasons to use on-demand, as on-demand can scale up and down quickly. Flexible start and end times is a criterion for choosing spot instances, and steady-state usage is ideal for reserved instances. Anytime you’re testing a new application, on-demand is a good choice
- Which of the following are reasons to select a spot instance? (Choose two.)
Applications with short-term, spiky workloads
Applications that have flexible start and end times
Applications with steady-state usage
Applications that are only feasible at very low compute prices
B, D. Applications with spiky workloads are reasons to use on-demand, as on-demand can scale up and down quickly. Flexible start and end times is a criterion for choosing spot instances, and steady-state usage is ideal for reserved instances. Spot instances also make heavy compute affordable when it would not be on other instance types.
- Which of the following are reasons to select the S3 standard storage class? (Choose two.)
Need for high durability
Need for highest available throughput
Infrequent access of objects
Objects can easily be re-created if lost.
A, B. S3 shares the durability of all S3 storage classes at 11 9s. It also provides the highest availability throughput of all S3 storage classes. Infrequent access is a use case for S3-IA, while the ability to re-create objects would suggest S3 One Zone-IA.
- You are the architect for a web application that exists on a cluster of EC2 instances all within an Auto Scaling group. During periods of high activity, the group scales up— adding instances—and then quickly scales back down. However, this occurs multiple times within a two-hour window, incurring significant costs. How could you reduce costs while ensuring that demand is still met? (Choose two.)
Modify the Auto Scaling group’s cool-down timers.
Modify the Auto Scaling group to use scheduled scaling.
Lower the CloudWatch alarm threshold that causes the Auto Scaling group to scale up.
Modify the CloudWatch alarm period that causes the Auto Scaling group to scale down.
A, D. The problem here is that instances are scaling down too quickly. This results in them then being restarted, which incurs cost. The solutions here should be ones that cause instances to stay around a bit longer, which meets demand. Both A and D do this. Cool-down timers increase the time for the group to ensure that previous scaling actions were completed (A), and the CloudWatch alarm period for scaling down should also be increased (D).
- You have a large archive of documents that must be backed up. The documents will be accessed very infrequently, if at all. However, when the documents are accessed, they must be delivered within 10 minutes of a retrieval request. What is the most cost-effective option for storing these documents?
S3
S3-IA
Glacier
Glacier with expedited retrieval
D. All the description here suggests using Glacier. The documents are a large archive, and many will never be accessed. However, the requirement for quick retrieval points to a need for expedited retrieval. Glacier with expedited retrieval is still going to cost less than S3-IA for access that isn’t that frequent.
- Your application has a 200 GB database running on an EC2 instance. You cannot move the database to RDS because of a custom spatial plug-in. The application is currently peaking in the morning and the evening, but the peaks are small and usage throughout the day is minimal. You need to ensure solid performance but keep costs low. What storage type would you use?
EFS
EBS with a General Purpose SSD
EBS with a provisioned IOPS SSD
EBS with a magnetic HDD
B. First, EBS is a much better choice than EFS for a single-instance application. While a database would certainly benefit from IOPS, there’s no need; peaks are small, and usage overall is low. A General Purpose SSD is sufficient here.
- Which EBS volume type is most appropriate for use with a large database workload?
EBS with a throughput optimized HDD
EBS with a General Purpose SSD
EBS with a provisioned IOPS SSD
EBS with a magnetic HDD
C. If you have a larger database workload, provisioned IOPS SSD is ideal.
- Your application currently stores all its data on EBS volumes. You want to ensure that these volumes are backed up durably. However, you also want to use as few different managed services as possible in order to keep backup costs low. What option would you recommend?
Take regular EBS snapshots manually.
Set up a Lambda function to take EBS snapshots and trigger the function through CloudWatch alarms.
Create a script to copy the EBS data to S3 and run it on an EC2 instance.
Mirror data across two EBS volumes.
A. This is a tough question. You can eliminate B and C because both involve additional services: CloudWatch, Lambda, and additional EC2 instances. Taking EBS snapshots is good, and by moving those snapshots into S3 (which is the default), you get durability automatically. Mirroring data is also a great option—providing fault tolerance—but this does not provide a durability component, something the question specifically requires. Therefore, A is the best answer.
- You are the architect for a highly available and highly scalable accounting application. All transaction records in the application’s data stores must be available for immediate retrieval for three months, but then they should be purged to reduce storage costs. How can you most easily address this requirement?
Store the transaction records on EBS and delete the volume after three months.
Store the transaction records in S3 and use lifecycle management to delete the records after three months.
Store the transaction records in Glacier and use lifecycle management to delete the records after three months.
Store the transaction records in EBS and use lifecycle management to delete the records after three months.
B. There are two components to this question: which storage medium is appropriate, and how should older records be deleted. To get both immediate retrieval and lifecycle management, you’d need S3, as in option B. (Also, EBS does not offer lifecycle management, in option D.)
- You want to optimize performance and cost of your application by creating a placement group rather than hosting separate copies of your application in multiple availability zones. Across how many availability zones can a placement group span?
One
One or more
Two or more
Placement groups are not in availability zones.
B. Placement groups are typically in a single availability zone, but now spread placement groups can be placed across availability zones.
- Across how many availability zones can a spread placement group be stretched?
One
One or more
Two or more
Placement groups are not in availability zones.
B. It is typical to think of a spread placement group as a group spread across availability zones, but that is a misnomer. The spread in spread placement group means that the instances are spread across distinct underlying hardware, and although they can be spread across availability zones, they don’t have to be.
- How many instances can run in a single availability zone for a spread placement group?
One
Five
Seven
Nine
C. A spread placement group can have a maximum of seven running instances per AZ.
- Which of the following are advantages of a spread placement group over using non-grouped instances? (Choose two.)
A spread placement group can span peered VPCs in the same region.
A spread placement group is less expensive than the same number of on-demand instances not in a group.
A spread placement group allows instances to talk with negligible network lag.
A spread placement group reduces IO in an instance within that group.
A, C. Spread placement groups primarily offer reduced network lag between instances (C). They also allow for cross-VPC spanning of instances (A).
- Which of the following statements about placement groups is false?
A spread placement group can span peered VPCs in the same region.
A clustered placement group has instances all in a single availability zone.
A spread placement group allows instances to talk across regions without network lag.
A clustered placement group involves fewer availability zones than a spread placement group.
C. The only false statement here is C: Spread placement groups cannot be set up across regions, and therefore this entire statement is untrue.
- Which of the following actions incur costs within AWS? (Choose two.)
Data ingress from the Internet
Data egress to the Internet
Transferring data across regions
Transferring data from one instance to another within the same availability zone
B, C. Egress always has a cost associated with it (B), while ingress is always free. Transferring data across regions is treated the same as transfers to the Internet. Only inter-AZ data transfer is guaranteed to be costless (D), making C the other correct answer.
- Which of the following costs the least?
Retrieving a file from S3 to a local desktop client
An instance retrieving data from S3 in the same region
Uploading a file to S3 from a local desktop client
An instance retrieving data from S3 in a different region
C. The least cost is always going to be “free,” so look for anything that might be ingress. In this cost, uploading to S3 is straight ingress and is therefore free and the cheapest option.
- Which of the following might help reduce data transfer costs? (Choose two.)
Set up CloudFront to cache content.
Ensure that any instances communicating with other instances in the same region have private IP addresses.
Set up an RDS instance with read replicas.
Set up S3 buckets with versioning.
A, B. First, CloudFront is always a good option. It’s free to move data from EC2 to CloudFront, so that could reduce how far data must travel, and associated costs. Then, private IPs allow for communication that doesn’t route out to the Internet, and generally AWS charges less for communication from private IP to private IP.
- Which of the following is not a level of AWS support?
Developer
Free tier
Enterprise
Business
B. Although there is a free tier, it’s a billing option and not an actual support level. That makes B the non-level in this answer set.
- Which of the following is reduced as part of AWS’s total cost of ownership approach?
Developer salaries
DevOps salaries
Capital expenditures
Organizational head count
C. AWS reduces the need for large capital expenditures and provides a pay-as-you-go model instead.
- Which of the following payment models does AWS employ to reduce total cost of ownership?
Pay up front
Pay-as-you-go
Pay after use
Quarterly pay
B. AWS uses a pay-as-you-go model for all of its services.
- Which of the following is not a key tenet of the AWS pricing philosophy?
Pay-as-you-go
Pay less when you reserve.
Pay less per unit by using more.
Pay more only when AWS grows.
D. D is incorrect; you actually pay even less as AWS grows, due to economies of scale.
