EC2

Question 1

What is EC2 in AWS?

Answer 1

A virtual server in the AWS cloud that is scalable, flexible, and pay-as-you-go.

Question 2

What are the 4 EC2 pricing models?

Answer 2

On-Demand, Spot, Reserved, Dedicated Host.

Question 3

When should you use On-Demand EC2?

Answer 3

For short-term, unpredictable workloads.

Question 4

When should you use Spot Instances?

Answer 4

For flexible jobs that can be interrupted; saves up to 90%.

Question 5

When should you use Reserved Instances?

Answer 5

For predictable workloads with 1–3 year commitments; saves up to 72%.

Question 6

When should you use Dedicated Hosts?

Answer 6

For licensing or compliance requirements; gives you physical hardware.

Question 7

What is User Data in EC2?

Answer 7

A bootstrap script that runs at instance launch with root permissions.

Question 8

What is Metadata in EC2?

Answer 8

Information about the EC2 instance (e.g., instance ID, IP address).

Question 9

What’s the default rule for EC2 security group inbound traffic?

Answer 9

All inbound traffic is blocked by default.

Question 10

What’s the default rule for EC2 security group outbound traffic?

Answer 10

All outbound traffic is allowed by default.

Question 11

Can EC2 security group changes be made live?

Answer 11

Yes, changes take effect immediately.

Question 12

Can multiple EC2 instances share the same security group?

Answer 12

Yes.

Question 13

What are IAM roles used for in EC2?

Answer 13

To give EC2 access to AWS services without hardcoding credentials.

Question 14

Can you attach/detach IAM roles without stopping the EC2 instance?

Answer 14

Yes.

Question 15

What are ENIs used for?

Answer 15

Basic networking, like separating management and production networks.

Question 16

What is Enhanced Networking used for?

Answer 16

High throughput (10–100 Gbps) and low latency.

Question 17

When should you use an Elastic Fabric Adapter (EFA)?

Answer 17

For high-performance computing or ML workloads.

Question 18

What are the 3 types of EC2 placement groups?

Answer 18

Cluster, Spread, Partition.

Question 19

Which placement group is best for low latency and high throughput?

Answer 19

Cluster Placement Group.

Question 20

Which placement group spreads instances across hardware?

Answer 20

Spread Placement Group.

Question 21

Which placement group is used for HDFS, Cassandra, or HBase?

Answer 21

Partition Placement Group.

Question 22

Can Cluster placement groups span Availability Zones?

Answer 22

No, only within a single AZ.

Question 23

What is required before moving an EC2 instance to a placement group?

Answer 23

The instance must be stopped.

Question 24

What are Dedicated Hosts ideal for?

Answer 24

Special software licenses or compliance rules.

Question 25

What is a Spot Block?

Answer 25

Prevents Spot Instances from being interrupted for a set duration.

Question 26

What is a Spot Fleet?

Answer 26

A collection of Spot (and optionally On-Demand) instances.

Question 27

What is vCenter on AWS used for?

Answer 27

Extending VMware environments to AWS for migration or disaster recovery.

Question 28

What is AWS Outposts?

Answer 28

Extends AWS infrastructure into your on-premises data center.

Question 29

What are the two types of AWS Outposts?

Answer 29

Outpost Racks (42U, for large deployments) and Outpost Servers (1U, for small/edge sites).

Question 30

Which AWS service should they use to run EC2 instances in their own data center?

Answer 30

AWS Outposts – Brings native EC2, EBS, and other AWS services to on-prem environments.

Question 31

Which placement group type should you use for a stateful web application that must maintain session data?

Answer 31

Partition Placement Group – Ideal for spreading instances across partitions (hardware racks and AZs) for fault tolerance.

Question 32

What must you do before changing the instance type in a Cluster Placement Group?

Answer 32

Stop the instance, change the instance type, and then restart it within the placement group.

Question 33

What EC2 networking feature enables connecting an instance to two separate subnets?

Answer 33

Elastic Network Interfaces (ENIs) – Attach multiple ENIs to assign the instance to different subnets.

Question 34

What should you enable to mitigate SSRF risks via the EC2 instance metadata endpoint?

Answer 34

IMDSv2 (Instance Metadata Service Version 2) – Requires session-based access to metadata, mitigating SSRF.

Question 35

Which should you use for Auto Scaling Groups: Launch Template or Launch Configuration?

Answer 35

Launch Template – Supports versioning and advanced EC2 features; Launch Configurations are legacy.

Question 36

Which EC2 deployment model supports SQL Server licenses tied to physical cores?

Answer 36

Dedicated Hosts – Provide control over physical server placement for licensing compliance.

Question 37

What EC2 feature should be enabled for automatic instance recovery on new hardware?

Answer 37

EC2 Auto Recovery – Automatically recovers the instance on new hardware in the same AZ.

Question 38

Which allocation strategy should be used to optimize Spot Fleet diversification?

Answer 38

Capacity Optimized – Chooses pools with the most available capacity to reduce interruption risk.

Question 39

Which EC2 feature should be enabled to increase disk throughput for a large database?

Answer 39

EBS-Optimized Instances – Provides dedicated network throughput for EBS volumes.