Hands-On Amazon VPC!

Amazon Virtual Private Cloud (VPC)

VPC enables you to launch AWS resources in a logically isolated virtual network that you define.

Availability Zones (AZs)

• Each AZ acts as an isolated data center location within a region, improving fault tolerance and redundancy.
  1. Availability Zone A

  • Contains:

    • Public Subnet (10.0.1.0/24)
    • Private Subnet (10.0.2.0/24)

1. Availability Zone B

   • Contains:

     • Public Subnet (10.0.3.0/24)
     • Private Subnet (10.0.4.0/24)

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Public Subnets

• Public Subnets are labeled:

  • AZ A → 10.0.1.0/24
  • AZ B → 10.0.3.0/24

These have direct routes to internet Gateway.

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Private Subnets

• Private Subnets are labeled:

  • AZ A → 10.0.2.0/24
  • AZ B → 10.0.4.0/24

These subnets are isolated from the internet — they don’t connect directly to the Internet Gateway. Instead, outbound internet traffic from private instances is routed through a NAT Gateway located in a public subnet.

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NAT Gateway

• It enables instances in private subnets to access the internet for downloading, packaging and updating.

• The diagram shows arrows from:

  • The Private Subnet (10.0.4.0/24) in AZ B
  • The Private Subnet (10.0.2.0/24) in AZ A Both connecting to the NAT Gateway, which in turn routes traffic to the Internet Gateway.

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Route Tables

• There is a Route Tables box, representing network routing configurations.

  • Public Subnet Route Table: Routes 0.0.0.0/0 traffic to the Internet Gateway.
  • Private Subnet Route Table: Routes 0.0.0.0/0 traffic to the NAT Gateway.

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Security Layers

1. Security Groups (SGs)

   • Function at the instance level.
   • Control inbound and outbound traffic for EC2 instances.
   • Typically allow HTTP/HTTPS/SSH for public instances and restricted access for private ones.

2. Network ACLs (NACLs)

   • Function at the subnet level.
   • Provide an additional layer of security that can allow or deny specific IP ranges.
   • Usually stateless, meaning inbound and outbound rules are separate.

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Interview Dose

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VPC Components

Component	Description	Use Case
Subnets	Logical subdivision of VPC	Separate public/private resources
Internet Gateway	Gateway to the internet	Enable internet access
NAT Gateway	Network Address Translation	Outbound internet for private subnets
Route Tables	Traffic routing rules	Control network traffic flow
Security Groups	Instance-level firewall	Stateful traffic filtering
NACLs	Subnet-level firewall	Stateless traffic filtering