AWS Virtual Private Cloud (VPC)

AWS Virtual Private Cloud (VPC) enables you to provision a logically isolated section of the AWS cloud where you can launch AWS resources in a virtual network that you define. VPC allows complete control over your virtual networking environment, including resource placement, connectivity, and security.

Key Features

• Subnets: VPCs can be divided into public and private subnets. Public subnets allow access to the internet, while private subnets do not.
• Route Tables: Control where network traffic is directed within your VPC. Each subnet must be associated with a route table.
• Internet Gateway (IGW): Attach an IGW to a VPC to allow communication between instances in the VPC and the internet.
• Network Access Control Lists (NACLs): Provide stateless traffic filtering for subnets within your VPC.
• Security Groups: Provide stateful filtering of inbound and outbound traffic at the instance level.
• VPN Gateway: Establish secure connections between your on-premises network and your AWS VPC using a VPN connection.

Architecture Overview

The following diagram illustrates how AWS VPC components work together to provide a secure and scalable virtual network:

• VPC: The main container for your subnets, route tables, security groups, and more.
• Subnets: Divide your VPC into smaller sections, each containing resources like EC2 instances.
• Route Tables: Determine how traffic is directed between subnets and to external networks.
• IGW: Enables communication between your VPC and the internet.
• NAT Gateway: Allows instances in a private subnet to access the internet without exposing them to incoming traffic from the internet.

Use Cases

• Secure Application Hosting: Host web applications in a public subnet and databases in a private subnet, ensuring separation of public and internal-facing resources.
• Hybrid Cloud Architectures: Extend your on-premises network into the cloud by creating a secure VPN connection to your VPC.
• Multi-Tier Applications: Implement multiple layers of security by placing different application components in separate subnets.
• Isolated Environments: Create multiple VPCs to isolate different environments such as development, staging, and production.

Integration with Other AWS Services

AWS VPC integrates with various AWS services to enhance security, scalability, and functionality:

• AWS EC2: Deploy instances in your VPC, associating them with specific subnets and security groups.
• AWS Lambda: Run serverless applications within your VPC, controlling access to VPC resources.
• AWS RDS: Deploy databases in a private subnet for enhanced security and control.
• AWS Direct Connect: Establish a dedicated network connection between your on-premises environment and your VPC for low-latency, high-throughput connectivity.

Things to Remember for the Exam

• Subnet Types: Understand the difference between public and private subnets and when to use each.
• Security Groups vs. NACLs: Know that security groups are stateful and operate at the instance level, while NACLs are stateless and operate at the subnet level.
• VPC Peering: Remember that VPC Peering connections allow resources in different VPCs to communicate as if they are within the same network.
• VPN Gateway: Understand how to set up a VPN connection to connect your on-premises network to your VPC securely.
• NAT Gateway vs. Bastion Host: Know the differences between NAT Gateways for outbound internet access from private subnets and Bastion Hosts for secure SSH access to instances in private subnets.