Real diagnostic scenarios and structured methodology for connectivity issues, routing problems, VLAN mismatches, STP loops, DNS and DHCP failures, wireless issues, firewall misconfigurations, latency, packet loss, and full outages.
This module deliberately covers failure modes that don't announce their own cause: a connectivity failure that looks identical whether it's a VLAN mismatch, a routing problem, or a firewall rule, or a hot neutral-style symptom — a hung connection on large transfers only — that points specifically at a path MTU black hole rather than a generic congestion problem. Every scenario follows the same discipline: what's actually observed in interface counters, routing tables, or a packet capture, what that observation rules in or out, and only then what fix follows from the diagnosis rather than a guess.
The module closes with a structured methodology for a full outage under real time pressure — establishing scope through bisection, checking what changed recently before anything else, and choosing a packet capture's vantage point deliberately once initial hypotheses run out — the same discipline this program's real-project modules expect you to already have.