Virtual Private Cloud (VPC)

Key components of VPC

The following are some key components that are important to establish and manage a networking environment:

• Subnets: Within a VPC, subnets are like smaller neighborhoods, dividing the overall IP address range into manageable segments. Each subnet is associated with a specific Availability Zone (AZ), which ensures redundancy and fault tolerance. For example, you might have one subnet for web servers and another for databases, each located in different AZs, to mitigate the impact of failures.

• Route tables: Think of route tables as traffic directors within the VPC. They determine how network traffic flows between subnets and external networks like the internet. For instance, a route table might specify that traffic destined for the internet should be directed through the internet gateway, while internal traffic stays within the VPC.

• Internet gateways: Internet gateways are the connection points between the VPC and the wider internet. They allow instances within the VPC to communicate with resources outside the VPC, such as websites, APIs, and external databases.

• Elastic IP addresses (EIP): EIPs are like reserved parking spots for instances within the VPC. They provide a static IP address that can be associated with an instance, ensuring that the instance maintains the same public-facing IP address even if it’s stopped and restarted.

Default VPC

By default, when you create an AWS account, AWS creates a default VPC for you in each AWS Region. The default VPC comes pre-configured with a set of default subnets, route tables, internet gateways, and network access control lists (ACLs). This simplifies the process of launching instances and other resources without needing to create a custom VPC. The default VPC comes pre-configured with the following settings:

• VPC configuration: A VPC with a size /16 IPv4 CIDR block (172.31.0.0/16), providing up to 65,536 private IPv4 addresses.

• Default subnets: A size /20 default subnet in each Availability Zone, providing up to 4,096 addresses per subnet. Some addresses are reserved for AWS use.

• Internet gateway: An internet gateway connected to the default VPC, allowing instances to communicate with the internet.

• Route configuration: A route in the main route table that points all traffic (0.0.0.0/0) to the internet gateway.

• Security group and network ACL: A default security group and network access control list (ACL) associated with the default VPC.

• DHCP options set: The default DHCP options set for your AWS account is associated with your default VPC.

Virtual Private Clouds (VPCs) are essential components of AWS infrastructure, providing users with isolated, customizable network environments for deploying their AWS resources. Default VPCs offer a convenient starting point for launching instances and experimenting with AWS services, while custom VPCs provide greater flexibility and control over network configurations. Understanding VPCs is crucial for designing scalable, secure, and resilient cloud architectures on AWS.