A VPC (Virtual Private Cloud) is a logically isolated section of the AWS Cloud where you can launch AWS resources in a virtual network that you define.
Key Facts
- Multiple VPCs can exist per AWS Region (default soft limit: 5 per Region, can be increased).
- Each VPC can have up to 5 IPv4 CIDR blocks.
- You define the IP address range for the VPC when creating it.
CIDR Block Constraints
- Minimum size:
/28→ 16 IP addresses.
- Maximum size:
/16→ 65,536 IP addresses.
Allowed Private IPv4 Ranges
10.0.0.0 – 10.255.255.255→ CIDR:10.0.0.0/8
172.16.0.0 – 172.31.255.255→ CIDR:172.16.0.0/12
192.168.0.0 – 192.168.255.255→ CIDR:192.168.0.0/16
Best Practice
Always choose non-overlapping CIDR ranges to prevent routing conflicts with:
- On-premises networks.
- Other VPCs you might peer or connect via VPN/Direct Connect.