04. VPC

VPC

---

Prerequisites

---

1. VPC

VPC is the networking foundation of AWS. It provides A logically isolated virtual network dedicated to your AWS account

A VPC (Virtual Private Cloud) is:

• A virtual network for your AWS resources
• Logically isolated from other networks
• Fully controlled by the user

VPC enables:

• Network isolation
• IP address control
• Traffic management
• Security configuration

Without VPC:

• Resources cannot communicate properly
• No control over network boundaries

✔️ Account-Dedicated Network

• Each VPC belongs to a single AWS account
• Completely isolated from other VPCs

✔️ Logical Isolation

• Even though infrastructure is shared physically
• Networks are separated logically

✔️ IP Address Space (CIDR)

This defines the address map of the VPC VPC defines its size using an IP range:

10.0.0.0/16

• A VPC exists within a single Region

2. How VPC

To build a VPC environment:

1. Define IP range (CIDR block)
2. Create subnets
3. Attach security groups
4. Configure route tables

Define network → segment it → secure it → route traffic

2-1. Subnet

A subnet is a smaller network inside a VPC.

VPC (10.0.0.0/16)
 ├── Subnet A (10.0.1.0/24)
 └── Subnet B (10.0.2.0/24)

• Each subnet exists in one Availability Zone
• Used for high availability architecture

Region
 └── VPC
      ├── Subnet (AZ-a)
      └── Subnet (AZ-b)

Type	Description
Public	Has route to Internet Gateway
Private	No direct internet access

2-2. Components

Many AWS services must be placed inside a VPC:

• EC2 (compute)
• RDS (managed database)
• ELB (load balancer)

When you create resources (EC2, RDS, ELB), they are placed inside a VPC

2-3. Internet Gateway (IGW)

• Enables internet access

EC2 → VPC → IGW → Internet

2-4. Route Table

Controls traffic flow:

Destination	Target
0.0.0.0/0	IGW

2-5. Security Group

• Instance-level firewall
• Stateful
• Allow rules only

2-6. NACL

• Subnet-level firewall
• Stateless
• Allow & deny rules

2-7. Putting It All Together

Internet
   ↓
[ Internet Gateway ]
   ↓
[ Public Subnet ] → EC2 (Web)
   ↓
[ Private Subnet ] → RDS / App

3. How to create VPC

3-1. Search VPC

3-2. Click Navigation pane → “Your VPCs”

3-3. Click Button → “Create VPC”

3-4. VPC settings

4. Related Concepts

• Components
  • Subnet
  • Internet Gateway
  • Router table
  • Nat Gateway