Level 1 · Core
Virtual machines
An instance launches, reports "running", and refuses every connection. Nothing is broken. Four separate things — a subnet route, a security group, a network ACL, and a key pair — all have to agree before a packet reaches your process.
Chapters
- How EC2 instances manage execution stateRenting a virtual machine means managing its lifecycle, but knowing what survives a stop, start, or termination helps you design resilient compute while keeping costs down.
- How EBS provides persistent block storageBlock storage volumes are physically pinned to single data centres to ensure low latency, but understanding snapshots and IOPS limits lets you move and scale compute storage safely.