Section 5: AWS EC2 Fundamentals, Security & Pricing

What is Amazon EC2?

EC2 is a virtual computer or server rented from AWS.

What is an EC2 instance?

A running virtual server created using EC2.

What is an AMI?

A template used to create an EC2 instance.

What is a security group?

A virtual firewall that controls traffic to and from an EC2 instance.

What is an inbound rule?

A rule controlling traffic coming into the instance.

What is an outbound rule?

A rule controlling traffic leaving the instance.

What is port 22 used for?

SSH access to a Linux server.

What is port 80 used for?

HTTP website traffic.

What is port 443 used for?

Secure HTTPS website traffic.

What is SSH?

A secure way to remotely control a Linux server.

What is EC2 Instance Connect?

A browser-based way to connect to a Linux EC2 instance.

What is an EC2 key pair?

A public and private key combination used for secure SSH access.

What is a .pem file?

The private key file used to connect to EC2 with SSH.

Why must a .pem file stay private?

Anyone with the file may be able to access the server.

What does Permission denied publickey usually mean?

The private key or username does not match the instance.

What is EC2 User Data?

A script that automatically configures an EC2 instance when it launches.

What does bootstrapping mean?

Automatically running setup commands when a server starts.

What does dnf install httpd do?

It installs the Apache web server.

What does systemctl start httpd do?

It starts Apache immediately.

What does systemctl enable httpd do?

It makes Apache start automatically after reboot.

Where is the default Apache webpage stored?

/var/www/html/index.html

What is a public IPv4 address?

An IP used to reach the EC2 instance through the internet.

What is a private IPv4 address?

An IP used inside the AWS private network.

What is an Elastic IP?

A fixed public IPv4 address.

What is an IAM role for EC2?

Permissions that an EC2 instance can temporarily use.

Why use an IAM role instead of access keys?

Roles provide temporary credentials without storing permanent keys.

What is EBS?

Persistent storage that acts like a virtual hard drive for EC2.

What is the difference between EC2 and EBS?

EC2 is the computer; EBS is the hard drive.

What does stopping an instance do?

It turns off the instance but keeps it and normally keeps its EBS data.

What does rebooting an instance do?

It restarts the instance without deleting it.

What does terminating an instance do?

It permanently deletes the instance.

What is a general-purpose instance?

A balanced instance for normal websites and applications.

What is a compute-optimized instance?

An instance designed for heavy CPU work.

What is a memory-optimized instance?

An instance designed for workloads needing lots of RAM.

What is a storage-optimized instance?

An instance designed for heavy and fast disk reading and writing.

What is accelerated computing?

Instances using GPUs or special hardware for AI, machine learning, and graphics.

What is On-Demand pricing?

Pay for EC2 as you use it with no long-term commitment.

When is On-Demand best?

Learning, testing, short-term projects, and unpredictable workloads.

What is a Savings Plan?

A 1-year or 3-year spending commitment that gives discounted compute prices.

What is a Reserved Instance?

A discount for committing to EC2 usage for 1 or 3 years.

What is a Spot Instance?

A cheap EC2 instance using AWS spare capacity that can be interrupted.

What workloads are good for Spot Instances?

Batch jobs, testing, rendering, and restartable workloads.

What workloads are bad for Spot Instances?

Critical databases and jobs that cannot be interrupted.

What is a Spot Fleet?

A group of Spot Instances used to meet a target amount of capacity.

What is a Dedicated Host?

An entire physical AWS server allocated to one customer.

Which EC2 option is best for a beginner lab?

On-Demand.

Which option is cheapest but interruptible?

Spot Instances.

Which option is best for steady long-term use?

Savings Plans or Reserved Instances.

Which option gives you an entire physical server?

Dedicated Host.

What is Auto Scaling?

It automatically adds or removes EC2 instances based on demand.

What is a load balancer?

It distributes traffic across multiple EC2 instances.

Why use multiple EC2 instances?

To improve availability, performance, and fault tolerance.