Amazon Web Service micro-instance initiation

Yes, it is possible to use a free AWS EC2 micro-instance with a Debian
distribution of Linux. Here are the steps to set it up:

1. **Sign in to AWS Management Console**: Navigate to [AWS Management
   Console](https://aws.amazon.com/console/).

2. **Launch an instance**:
   - Go to the EC2 Dashboard and click on "Launch Instance".
   - Choose a "Quick Start" AMI. You can search for "Debian" in the
     search bar.

3. **Select the "Free tier eligible" instance type**:
   - Choose "t2.micro" or "t3.micro" (both are free tier-eligible).

4. **Configure Instance Details**: You can leave the default settings
   or adjust them according to your needs.

5. **Add Storage**: The default storage settings are usually
   sufficient for a micro-instance, but you can adjust them if needed.

6. **Add Tags**: Optionally, add tags to help you identify the
   instance.

7. **Configure Security Group**:
   - Add rules to allow SSH (port 22) so you can connect to your
     instance.
   - Add any other rules required for your application.

8. **Review and Launch**:
   - Review your settings and click "Launch".
   - Select or create a new key pair to connect to your instance
     securely and click "Launch Instances".

9. **Connect to your instance**:
   - Once the instance is running, select it and click on "Connect".
   - Follow the provided instructions to SSH into your Debian instance
     using the key pair you downloaded.

This will give you a Debian-based micro-instance running on AWS,
within the free tier limits.

The primary differences between "t2.micro" and "t3.micro" instances on
AWS are related to performance characteristics, pricing, and
underlying technology. Here's a concise comparison:

### Performance

- **T2 Instances**:
  - **Baseline Performance:** T2 instances provide a baseline level of
    CPU performance with the ability to burst above the baseline for a
    short time.
  - **CPU Credits:** They accumulate CPU credits when idle and consume
    credits while bursting. If the credits are exhausted, the instance
    will be throttled.

- **T3 Instances**:
  - **Enhanced Baseline:** T3 instances generally offer better
    baseline performance compared to T2.
  - **CPU Credits:** Similar to T2 in that they use CPU credits, but
    T3 instances have the additional advantage of **Unlimited Mode**
    by default, where they can sustain high CPU performance without
    being throttled, and you pay for any extra usage beyond the
    baseline.

### Pricing

- **T2 Instances**:
  - Often slightly cheaper than T3 instances.
  - Typically used for consistent, low-CPU-bound workloads.

- **T3 Instances**:
  - Slightly more expensive but more cost-efficient for variable
    workloads due to their improved baseline performance and CPU
    credit management.

### Technology

- **T2 Instances**:
  - Earlier generation, generally based on Intel processors (older
    versions).
  - EBS-optimized option available but might lower IOPS compared to
    T3.

- **T3 Instances**:
  - Newer generation, often based on AWS Nitro System, which provides
    better network performance and flexibility.
  - Generally more efficient and capable compared to T2.
  - Support for both Intel and AMD processors.

### Summary

- **T2.micro**: Suitable for consistent workloads with occasional
  bursts, slightly cheaper.
- **T3.micro**: Better for variable workloads with frequent bursting
  needs, more efficient use of CPU credits, and enhanced networking
  capabilities.

Choosing between the two depends on your specific use case regarding
performance requirements and cost considerations.

When you create a subnet within a VPC with the default IPv4 CIDR block
`172.31.0.0/16`, you need to specify a smaller CIDR block for the
subnet that falls within the range of the VPC's CIDR block. Here’s how
you can determine and specify an appropriate CIDR block for your
subnet:

### Example Subnet CIDR Blocks

For a default VPC CIDR block of `172.31.0.0/16`, here are some
examples of valid subnet CIDR blocks that adhere to common subnetting
practices:

#### /24 subnet (256 IP addresses)
- `172.31.0.0/24`
- `172.31.1.0/24`
- `172.31.2.0/24`
- ...
- `172.31.255.0/24`

#### /20 subnet (4096 IP addresses)
- `172.31.0.0/20`
- `172.31.16.0/20`
- `172.31.32.0/20`
- ...
- `172.31.240.0/20`

#### /28 subnet (16 IP addresses)
- `172.31.0.0/28`
- `172.31.0.16/28`
- `172.31.0.32/28`
- ...
- `172.31.255.240/28`

### Steps to Create a Subnet

1. **Navigate to the VPC Dashboard**: In the AWS Management Console,
   go to the VPC Dashboard.
2. **Select the VPC**: Choose the VPC with the CIDR block
   `172.31.0.0/16`.
3. **Create Subnet**:
   - Click on "Create Subnet".
   - Select the VPC you want to create the subnet in.
   - Specify the `Subnet Name` for easy identification.
   - Choose the Availability Zone where you want the subnet to
     reside. You can also select "No Preference".
   - Enter the IPv4 CIDR block for the subnet. For example:
     - `172.31.1.0/24` for a /24 subnet providing 256 addresses
     - Or use a smaller or larger subnet mask based on your
       requirements, such as /20 for more addresses or /28 for fewer.

### Important Points to Consider:
- **Address Size**: Smaller subnet masks like /20 provide more IP
  addresses but fewer subnets, whereas larger subnet masks like /28
  provide fewer IP addresses but more subnets.
- **Overlapping**: Ensure that the subnet CIDR block does not overlap
  with another subnet in the same VPC.
- **Size Allocation**: Think about future scaling—it's often a good
  idea to leave some space for additional subnets later.

By following these practices, you can effectively manage and allocate
IP addresses within your VPC.

Yes, you are correct. If you are unable to locate the `emacs` package,
it's often because the package repositories are not properly
configured. Here are the steps to configure your repositories and
install `emacs` on your Debian AWS instance:

1. **Update Package Lists**: First, update the package lists to ensure they are up to date.
   ```sh
   sudo apt update
   ```

2. **Check Sources List**: Ensure that the sources list file has the necessary repositories. The sources list file is usually located at `/etc/apt/sources.list`. You can check its contents with:
   ```sh
   cat /etc/apt/sources.list
   ```

3. **Edit Sources List**: If necessary, edit the sources list file to include the official Debian repositories. Use a text editor like nano or vim:
   ```sh
   sudo nano /etc/apt/sources.list
   ```
   Make sure it includes lines similar to the following (replace `buster` with your Debian version if different):
   ```sh
   deb http://deb.debian.org/debian buster main
   deb http://deb.debian.org/debian buster-updates main
   deb http://deb.debian.org/debian buster-backports main
   deb http://security.debian.org/debian-security buster/updates main
   ```

4. **Update Package Lists Again**: After saving any changes to the sources list, run the following command again to update the package lists:
   ```sh
   sudo apt update
   ```

5. **Install Emacs**: Now, try to install `emacs` again:
   ```sh
   sudo apt install emacs
   ```

### Example:
```sh
sudo apt update
sudo apt install emacs
```

These steps should configure the repositories correctly and allow you
to install `emacs` on your Debian AWS instance.

If you want to install `Emacs` without X support (i.e., the text-only
version of Emacs that runs in the terminal), you should install the
package `emacs-nox`. This version of Emacs is designed to run without
any graphical user interface.

Here’s how you can do it:

1. **Update Package Lists**: Always a good practice to update the package lists to ensure you get the latest information.
   ```sh
   sudo apt update
   ```

2. **Install Emacs without X Support**:
   ```sh
   sudo apt install emacs-nox
   ```

This will install the Emacs text editor without any X dependencies,
allowing you to run it entirely within the terminal.

### Example:
```sh
sudo apt update
sudo apt install emacs-nox
```

By installing `emacs-nox`, you'll be able to use Emacs in a terminal
environment without the overhead of graphical components.