VPCs, Subnets, Route Tables & The Internet Gateway
Why can a customer reach your web server in a Public Subnet, while your database in a Private Subnet stays completely invisible to the outside world?
Toggle the routing switches on the right and fire test packets to see the three things required for internet connectivity.
🗺️
The Big Secret: AWS doesn't have a magic button that makes a subnet "Public."
Every subnet starts out completely private! A room (Subnet) only becomes Public when you:
(1) build a front gate on your campus (Internet Gateway),
(2) put a sign on the hallway map (Route Table) pointing outside traffic (0.0.0.0/0) to that gate, and
(3) give the server inside a public street address (Public IP).