Every service you'll ever deploy talks to something else over a network, so understanding how that traffic actually moves matters as much as knowing your way around a shell. This module covers the OSI and TCP/IP models, IP addressing and subnetting, how DNS turns names into addresses, and the difference between TCP and UDP at the transport layer.
From there it moves into the pieces you'll configure directly in a DevOps role: HTTP/HTTPS traffic, firewalls and security groups, load balancing, secure remote access with SSH and VPNs, and the command-line tools you'll reach for when something isn't connecting.
Watch the lessons in order, then continue on to Version Control & Hosting.
How the two reference models describe network communication in layers, and why thinking in layers makes troubleshooting far more systematic.
IPv4 and IPv6 addresses, CIDR notation, and how subnetting carves up a network into smaller, manageable segments.
The journey from typing a domain name to getting back an IP address — resolvers, root servers, record types, and TTLs.
Why TCP's handshake and reliability guarantees suit some workloads while UDP's speed and simplicity suit others.
Requests, responses, status codes, and how TLS wraps HTTP in encryption to keep traffic private and verified.
Controlling inbound and outbound traffic at the host and cloud level, and how security groups differ from network ACLs.
Why traffic gets distributed across multiple servers, common algorithms, and the difference between layer 4 and layer 7 load balancers.
Connecting to remote servers safely with SSH keys, and how VPNs extend a private network across the public internet.
Diagnosing connectivity issues with ping, traceroute, curl, dig, and netstat — the first commands to reach for when something won't connect.