Subnets

Public and Private Network Segments

Public Subnets

Subnets with direct internet access through Internet Gateway.

Route to Internet Gateway (0.0.0.0/0)
Auto-assign public IP addresses
Web servers, load balancers

Private Subnets

Subnets without direct internet access, using NAT for outbound traffic.

Route to NAT Gateway/Instance
No public IP addresses
Databases, application servers

Availability Zones

High Availability

Deploy subnets across multiple AZs for fault tolerance

Load Distribution

Spread resources across AZs for better performance

Subnets Exam Tips

  • • Public subnets have route to Internet Gateway (0.0.0.0/0 → IGW)
  • • Private subnets route internet traffic through NAT Gateway/Instance
  • • Each subnet exists in exactly one Availability Zone
  • • AWS reserves 5 IP addresses in each subnet (first 4 and last 1)
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