A VPC spans all of the Availability Zones in a Region. After you create a VPC, you can add one or more subnets in each Availability Zone.

Each VPC comes with the following resources:

1. Default Network ACL
2. Default Security Group
3. Main Route Table
4. Default DHCP option set (DNS servers, Domain Name, NTP)

CIDR - Classless Inter Domain Routing

• Method for allocating IP address
• 192.168.0.0/26 → 192.168.0.0 - 192.168.0.63 (64 IP addresses)
• Base IP + Subnet Mask (/0, /8, /16,/24, /32)

Subnet Mask

• /8 ⇒ subnet mask of 255.0.0.0 (2^8-1)
• /16 ⇒ 255.255.0.0
• /24⇒ 255.255.255.0
• /32 ⇒ 255.255.255.255

/32 → 1 IP (2^0 Ips) , so if base ip is 192.168.0.0/32 → 192.168.0.0 → no octet can change