Networking Cheat Sheet¶

Scannable commands and patterns for the Networking track. Prefer the full tutorials when you need why, not only how.

Quick reference¶

Area	Commands / notes
Models	OSI vs TCP/IP layers; which headers live where
Addressing	CIDR math; private ranges; broadcast vs unicast
DNS	`dig +trace`; `dig A/AAAA/CNAME/MX`; TTL behaviour
Sockets	`ss -tulpn`; ephemeral ports; TIME_WAIT
HTTP	Methods, status codes, TLS handshake overview
Routing	`ip route`; default gateway; traceroute/mtr
Firewall	iptables/nftables / cloud SG mental model
LB / proxy	L4 vs L7; reverse proxy vs ingress
Capture	`tcpdump -ni eth0 port 443`; Wireshark follow stream
VPN	Tunnel vs transport; common split-tunnel pitfalls
Segmentation	Internet → edge → app → data; mgmt separate
DNS ops	TTL before cutover; dig vs getent; split-horizon
LB ops	Health check path; drain before stop; sticky trade-offs
ACL change	Console access first; canary; documented rollback
IR first hour	Scope → curl/dig/ss → mtr → tcpdump if needed