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AWS Certified Solutions Architectn CO3 > EC2 101 > Flashcards

EC2 101 Flashcards

EC2 High Level Principles, Pricing Models, Pricing Scenarios

1
Q

What does EC2 stand for?

A

Elastic Compute Cloud

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2
Q

At a high level, what does EC2 provide?

A

EC2 is a web service that provides resizeable compute capacity in the cloud

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3
Q

Why is EC2 useful?

A
  • EC2 reduces the time required to obtain & boot new server instances to minutes.
  • This allows you to quickly scale capacity (both up and down) as computing requirements change
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4
Q

What are the 4 core principles behind the EC2 pricing model?

A
  • Pay as you go
  • Pay for what you use
  • Pay less as you use more
  • Pay even less as you reserve capacity
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5
Q

What are the 4 EC2 Pricing Models?

A
  • On Demand
  • Reserved
  • Spot
  • Dedicated Hosts
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6
Q

How does On Demand Pricing for EC2 instances work?

A

Pay a fixed rate by the hour (or second) with no time commitment

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7
Q

At a high level, how does Reserved Pricing for EC2 instances work?

A

Reserved Pricing provides you with a capacity reservation, at a significant discount on the hourly rate.

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8
Q

How long is the contract on a Reserved Instance in EC2?

A

Can be 1 year or 3 years

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9
Q

A user is developing and testing an application using EC2 for the first time. Which EC2 pricing model best suits their use case?

A

On Demand Pricing

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10
Q

A user’s application requires a reserved capacity, and they are able to make upfront payments to save money. Which pricing model makes the most sense in this scenario?

A

Reserved Pricing

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11
Q

What are the three types of Reserved Instances Classes?

A
  • Standard Reserved Instances
  • Convertible Reserved Instances
  • Scheduled Reserved Instances
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12
Q

What is the key difference between a Standard Reserved Instance and a Convertible Reserved Instance?

A
  • A Convertible Reserved Instance is more flexible on the fly.
  • In general, you can change the attributes of a convertible reserved instance as long as the change results in a reserved instance class of equal or lesser value.
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13
Q

What is the best way to purchase compute capacity reservations that do not run continuously, but do recur on a regular schedule (daily, weekly, monthly)

A

Use Scheduled Reserved Instances

(Source)

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14
Q

How do EC2 Spot Instances work?

A

When EC2 has unusued capacity, Amazon drops the price of instances, so you can bid whatever price you want for instance capacity (“Free market”)

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15
Q

An application has an urgent computing need that calls for large amounts of additional compute capacity. Which EC2 pricing model makes the most sense for this use case?

A

Spot Instances

(On-Demand might also work here but will be costlier. Spot is better since we need additional compute. Spot should not handle 100% of your compute capacity)

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16
Q

If a Spot Instance is terminated by Amazon EC2 after you have used it for 2.5 hours, how much are you charged for it?

A

2 hours at whatever price you bid for it.

If a Spot instance is terminated by EC2 (called a Spot Instance Interruption), you are not charged for the partial hour in which it ran.

17
Q

If you terminate a spot instance after using it for 2.5 hours, how much do you pay for using the instance?

A

3 hours at whatever price you bid for it.

If you terminate a spot instance, you are charged for any hour in which the instance ran.

18
Q

What is a Dedicated Host?

A

A Dedicated Host is a physical EC2 server dedicated for your use.

19
Q

A user wants to use an existing server-bound software license to reduce compute costs. Which pricing model makes the most sense for this use case?

A

Dedicated Hosts

20
Q

What is the pricing model for Dedicated Hosts?

A
  • Dedicated Hosts can be purchased on-demand (hourly)
  • Dedicated Hosts can be purchased as a reservation for up to 70% off the on-demand price.
21
Q

What is Termination Protection for EC2 instances?

A
  • Termination Protection helps prevent you from accidentally terminating your instances
22
Q

On an EBS-backed EC2 instance, assuming default settings, what happens to the root EBS volume once the instance is terminated?

A

The root EBS volume is deleted

23
Q

An application has short-term, spiky, or unpredictable workloads that cannot be interrupted. Which EC2 pricing model makes the most sense for this use case?

A

On-Demand Pricing

(Spot would not work since it can be interrupted)

24
Q

A user wants the low cost and flexibility of EC2 but does not want to make a long-term commitment or an up-front payment. Which EC2 pricing model makes the most sense for this use case?

A

On-Demand Pricing

(Reserved is a long-term commitment;
Spot is not as much flexibility)

25
Q

An application has steady-state and predictable usage. Which EC2 pricing model makes the most sense for this use case?

A

Reserved Instances

26
Q

A users application requires a reserved capacity. What is the best pricing model for this use case?

A

Reserved EC2 Pricing

27
Q

A user’s application has flexible start and end times. Which pricing model makes the most sense in this scenario?

A

Spot Instance Pricing

28
Q

A user’s application is only feasible at low compute prices. Which pricing model makes the most sense for this use case?

A

Spot Instances

29
Q

A User’s license does not support multi-tenancy of cloud deployments. Which EC2 pricing model makes the most sense for this use case?

A

Dedicated Hosts

30
Q

A User’s regulatory requirements do not support multi-tenant virtualization. Which pricing model makes the most sense for this use case?

A

Dedicated Hosts

31
Q

Is Termination Protection for EC2 instances enabled by default?

A

No

32
Q

What is bootstrapping?

A

Launching commands when (and only when) a machine starts

33
Q

What is the purpose of EC2 User Data ?

A

EC2 User Data is used to automate bootstrap tasks for an EC2 instance

34
Q

Suppose you want to execute a command right when your EC2 instance starts up. What is the best way to do that?

A

Put the command in the EC2 User Data

AWS Certified Solutions Architectn CO3 (59 decks)

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