Technicians
Take any network symptom, name the one layer it lives at, and name the first command or setting to check, instead of guessing. Seven sessions, wire to wireless.
The sessions teach the job, not the test. Each one maps to a domain of the CompTIA Network+ N10-009 exam and names the chapters of the Network+ Study Guide that cover the same material. Domain 5.0, Network Troubleshooting, runs through every session. Want the whole book instead? Open the Study Guide companion.
The layer model and the address: the two ideas every later session leans on.
Study guide: chapters 2, 6
The seven OSI layers and the four TCP/IP layers, the MAC address and the IP address and why a device carries both, encapsulation, the six ports to know, and the bottom-up check that drives a symptom to one layer.
Study guide: chapters 7, 8
Binary, the subnet mask, network and broadcast addresses, slash notation and the host count, the private ranges, splitting a network, and the one test a device runs before it sends anything.
Switches inside a network, routers between networks, and the services that hand out addresses and names.
Study guide: chapters 4, 11
How a switch builds its address table, the broadcast domain, what a VLAN changes and what it does not, access and trunk ports and their two settings, PoE and power budgets, loops and spanning tree.
Study guide: chapters 9, 10, 19
The routing table on a workstation, the default route, longest prefix match, how traffic crosses between VLANs, static routes and the return path, reading a trace, and the four places a packet stops.
Study guide: chapters 5, 6, 19
The four settings in a lease, the four-message exchange, why a failure produces symptoms hours later, reservations against static addresses, a second DHCP server, the order a name is resolved in, and time to live.
What the firewall lets through, and the network without wires.
Study guide: chapters 5, 8, 20, 21
Stateful inspection and why a reply gets back in, rule order and the implicit deny, zones, address translation worked through, port forwarding and what it exposes, VPN as its own zone, and reading a blocked-traffic log.
Study guide: chapter 12
The shared medium and airtime, the three bands, channels and overlap, channel width, reading signal against noise, roaming, mapping a wireless network to a VLAN, and the four questions behind a slow wireless report.