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TEC-ITS43-05 · Lesson 4 · 13.5 clock hours · lab

Compute Services: Virtual Machines in the Cloud

Objective. Students will launch, connect to, stop, resize, and terminate a cloud virtual machine instance, and explain how instance types, AMIs (or equivalent images), and key pairs function.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by an industry-certified professional or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

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What Is a Cloud Virtual Machine?

A cloud virtual machine (VM) is a software-defined computer that runs on physical hardware managed by a cloud provider. Instead of buying and racking a server, you request one through a web console or API, and the provider allocates CPU, memory, and storage from its data center to your instance within minutes. The three largest providers—Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP)—all offer this service under different names (EC2 instances, Virtual Machines, and Compute Engine instances, respectively). This lesson uses AWS terminology because it is the most widely referenced in CompTIA and Cisco study materials, but the concepts transfer directly.

Instance Types

An instance type defines the hardware profile of your VM: how many virtual CPUs (vCPUs) it gets, how much RAM, and what network performance to expect. AWS organizes instance types into families by workload. The t family (for example, t2.micro, t3.micro) is designed for general-purpose, burstable workloads and is the most common choice for labs and low-traffic applications. The m family targets balanced compute and memory. The c family is compute-optimized for CPU-heavy tasks, and the r family is memory-optimized for databases and in-memory caching.

For certification labs and small deployments, the t2.micro or t3.micro is the standard free-tier option. Free-tier eligibility is important in a training environment because it avoids unexpected charges. Always confirm which instance type qualifies under the current AWS Free Tier offer before launching.

Amazon Machine Images (AMIs)

An AMI is a template that contains the operating system, initial software configuration, and sometimes pre-installed applications for a new instance. Think of an AMI the way you think of a hard-drive image used to deploy workstations on a corporate network. When you launch an instance, you select an AMI first, and the provider copies that image to your new virtual disk.

AMIs are classified by source:

For this lab you will choose a Quick Start AMI running Amazon Linux 2 or Ubuntu LTS because both are free-tier eligible and well-documented.

Key Pairs and Secure Access

Before an SSH-based Linux instance is reachable, you must associate a key pair with it. A key pair consists of a public key (stored by AWS on your instance) and a private key (downloaded to your machine as a .pem file on macOS/Linux or converted to .ppk for PuTTY on Windows). The private key proves your identity without sending a password over the network.

Handle your private key carefully. If it is lost, you cannot recover it from AWS; you would need to create a new key pair. If it is exposed, anyone who has it can connect to your instance. Store the .pem file in a directory with restricted permissions (`chmod 400 keyname.pem` on Linux/macOS).

Security Groups

A security group is a virtual firewall attached to an instance. It contains inbound and outbound rules specifying which protocols, ports, and source IP ranges are allowed. To connect to a Linux instance via SSH, you need an inbound rule permitting TCP port 22. Best practice is to restrict the source to your own public IP address rather than allowing all IP addresses (0.0.0.0/0), which exposes the instance to the entire internet.

Stopping, Resizing, and Terminating Instances

Resizing is a key advantage of cloud compute over physical hardware—what would require a technician to open a server and swap RAM chips takes a few clicks in the console.

Safety and Professional Practices

Cloud labs do not involve electrical hazards the way physical hardware does, but there are real risks:

Connecting via SSH

On macOS or Linux, open Terminal and run:

```

ssh -i /path/to/keyname.pem ec2-user@<Public-IP-Address>

```

On Windows, use PuTTY with the .ppk version of your key (converted using PuTTYgen). The default username depends on the AMI: `ec2-user` for Amazon Linux, `ubuntu` for Ubuntu, and `Administrator` for Windows (accessed via RDP, not SSH).

Once connected, you have a command prompt on a remote Linux server running in a data center—this is the foundation of cloud administration.

Key terms8

Instance typeA predefined hardware profile for a cloud VM specifying the number of virtual CPUs, amount of RAM, and network performance characteristics (for example, t2.micro, m5.large).
AMI (Amazon Machine Image)A template containing an operating system and optional software that AWS uses to create the root disk of a new EC2 instance.
Key pairA matched public/private key set used to authenticate SSH access to a Linux cloud instance; the public key is stored on the instance and the private key (.pem file) is kept by the user.
Security groupA stateful virtual firewall applied to a cloud instance that controls inbound and outbound traffic by protocol, port, and source/destination IP range.
Elastic IPA static public IPv4 address in AWS that remains assigned to your account and can be associated with an instance so the IP does not change across stop/start cycles.
Free TierA usage allowance offered by cloud providers (including AWS) that lets new or qualified accounts run certain instance types and use limited storage at no charge for a defined period.
SSH (Secure Shell)A cryptographic network protocol used to log in to and execute commands on remote systems securely over an unsecured network, typically on TCP port 22.
Instance terminationThe permanent deletion of a cloud VM instance and, by default, its root storage volume; this action cannot be undone.
In class: Guided lab: students launch a t2.micro (or equivalent free-tier) Linux instance, select a public AMI, create and download a key pair, assign a security group allowing SSH, and connect via SSH from their local machine. · Students stop the instance, change the instance type to another free-tier option, restart it, and verify that the public IP has changed; they record observations in their lab log. · Partner activity: one student acts as the 'caller' describing a business need (e.g., 'we need a Windows server for a small file share'); the partner selects an appropriate instance type and image from the console and justifies the choice.
Materials: Student laptops, cloud lab sandbox or AWS Free Tier, SSH client (PuTTY on Windows or built-in terminal on macOS/Linux), lab log template, CompTIA A+ Core 2 study guide (virtualization section)
Check: Students submit a screenshot of a running instance with a verified SSH session open and a completed lab log entry describing instance type, AMI ID, and key pair use; instructor confirms SSH access and log accuracy.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

CompTIA A+ Core 2 – Virtualization and Cloud Computing
1. A student launches a Linux EC2 instance, stops it, and restarts it. They notice the public IP address is different. What is the most likely reason?
CompTIA A+ Core 2 – Virtualization and Cloud Computing
2. Which of the following best describes the purpose of an AMI?
CompTIA Network+ – Cloud Concepts
3. A technician wants to resize a running EC2 instance to a larger instance type. What must be done before the instance type can be changed?
CompTIA A+ Core 2 – Troubleshooting
4. A student downloads a .pem private key file and tries to SSH into a Linux instance. The connection is refused. The security group has an inbound rule allowing TCP port 22 from all addresses. What should the student check NEXT?
CompTIA Network+ – Network Security
5. Which security group configuration follows the principle of least privilege when allowing SSH access for a lab student?
CompTIA A+ Core 2 – Virtualization and Cloud Computing
6. A partner activity requires selecting an instance for a small Windows file server. Which combination is most appropriate?
CompTIA A+ Core 2 – Virtualization and Cloud Computing
7. In AWS, what happens to an EC2 instance's root EBS volume by default when the instance is terminated?
Cisco CCNA – Cloud and Virtualization Fundamentals
8. Which of the following best describes a key advantage of cloud virtual machines over equivalent on-premises physical servers in a networking support context?
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