EC2 Fundementals

Question 1

What does EC2 stand for?

Answer 1

Elastic Compute Cloud

Question 2

What are the core capabilities of EC2?

Answer 2

Renting VMs, EBS storage, ELB for load balancing, ASG for scaling.

Question 3

What is EC2 User Data used for?

Answer 3

Running a script at first boot to install packages, updates, or configure the instance.

Question 4

Does EC2 User Data run every time the instance starts?

Answer 4

No, it runs only at the first launch.

Question 5

What does EC2 user data script run as?

Answer 5

It runs as the root user.

Question 6

What are the configuration options when launching an EC2 instance?

Answer 6

OS, CPU, RAM, Storage, Network, Security Group, EC2 User Data.

Question 7

What is the EC2 instance naming convention format?

Answer 7

Example: m5.2xlarge – class, generation, size.

Question 8

What is a General Purpose EC2 instance good for?

Answer 8

Balanced compute, memory, networking – good for web servers.

Question 9

What workloads suit Compute Optimized EC2 instances?

Answer 9

Batch processing, HPC, gaming servers, media transcoding.

Question 10

What are Memory Optimized instances best used for?

Answer 10

Large in-memory data processing, BI apps, high-perf databases.

Question 11

When should you use Storage Optimized instances?

Answer 11

High IOPS tasks, OLTP, data warehousing, cache, file systems.

Question 12

What is the function of a Security Group in EC2?

Answer 12

It acts as a virtual firewall to control inbound and outbound traffic.

Question 13

Do security groups allow DENY rules?

Answer 13

No, only ALLOW rules are permitted.

Question 14

What happens if your app times out on EC2?

Answer 14

Likely a security group issue.

Question 15

What happens if your app gives a connection refused error?

Answer 15

Likely the app isn’t running or configured incorrectly.

Question 16

What are some classic ports to know for EC2?

Answer 16

22-SSH, 21-FTP, 80-HTTP, 443-HTTPS, 3389-RDP.

Question 17

What is EC2 Instance Connect?

Answer 17

Browser-based SSH access without downloading a key file.

Question 18

What EC2 OS is required for EC2 Instance Connect to work out-of-the-box?

Answer 18

Amazon Linux 2.

Question 19

What are EC2 On-Demand instances best for?

Answer 19

Short-term, unpredictable workloads.

Question 20

How are EC2 On-Demand instances billed?

Answer 20

Per second (Linux/Windows) or per hour (others).

Question 21

What are EC2 Reserved Instances best for?

Answer 21

Steady-state usage, long-term workloads.

Question 22

What is a Convertible Reserved Instance?

Answer 22

RI that allows change in instance family, type, OS, etc.

Question 23

What are EC2 Savings Plans?

Answer 23

Discounted pricing based on commitment to usage ($/hr for 1–3 years).

Question 24

How much can you save with EC2 Spot Instances?

Answer 24

Up to 90% compared to On-Demand.

Question 25

When should you NOT use Spot Instances?

Answer 25

Critical workloads or databases.

Question 26

What is an EC2 Dedicated Host?

Answer 26

Entire physical server dedicated to your use, good for BYOL.

Question 27

What is the main difference between Dedicated Host and Dedicated Instance?

Answer 27

Dedicated Host gives control over placement; Dedicated Instance does not.

Question 28

What is an EC2 Capacity Reservation?

Answer 28

Reserves EC2 capacity in a specific AZ; billed at On-Demand rates.

Question 29

When did AWS start charging for IPv4 addresses?

Answer 29

February 1, 2024.

Question 30

How much does AWS charge for Public IPv4?

Answer 30

$0.005 per hour (~$3.60 per month).

Question 31

Is there a free IPv4 tier?

Answer 31

Yes, 750 hours/month for first 12 months for new accounts.

Question 32

Why isn't IPv6 widely used?

Answer 32

Many ISPs still don’t support IPv6.