Mentora
Classytic

Course

Computer Networks: how far does it reach, and who can see it

Build a network from the cable up. Wire a plug, watch a switch learn, move a prefix line and see two machines stop being neighbours, then work out exactly who can read your traffic and what a VPN does about it.

69 lessons6h 28mEnglish

What you'll learn

  • Choose a transmission medium by ruling the others out, using distance, interference and movement
  • Wire an RJ45 plug to T568B and say why the blue pair sits on the middle two pins
  • Explain how a switch builds its address table without being configured, and what it does before it has one
  • Say which address in a frame is rewritten at every hop and which one is not, and why both are needed
  • Decide whether two IPv4 addresses share a network by comparing them in binary
  • Work out the network address, broadcast address and usable host count for a given prefix
  • Explain what a VLAN is in terms of what a broadcast reaches, and what a layer-3 interface adds
  • Calculate what a set of headers costs and say when that cost matters
  • Name what each party on a network path can observe about your traffic
  • Judge a VPN offer on what the provider gains rather than on what the advertising claims
  • Trace opening a real application connection through DNS, TCP and TLS rather than treating the URL as magic
  • Predict when a bottleneck begins adding delay and when its finite queue begins dropping packets
  • Follow one message from composition to delivery, including what happens to offline recipients
  • Locate a home connectivity failure by identifying the last network boundary that still works
  • Publish a local service through DNS, a router port-forward, the host firewall and a real listening process
  • Explain why Nginx can provide a stable public boundary without increasing the application’s compute capacity
  • Distinguish a reachability failure from overload by observing the route, queueing delay and rejected work
  • Trace a DHCP lease and explain why an ICE call may use a direct mapping or a TURN relay
  • Calculate the usable TCP send window and predict how acknowledgements, duplicate ACKs and timeouts change it
  • Build IPv6 reachability from link-local identity, router advertisements, SLAAC and neighbor discovery
  • Choose an OSPF path by cost and explain why BGP policy may choose a longer AS path

Requirements

  • Comfort with binary and powers of two. Chapter 3 works in bits and the arithmetic is not explained again
  • No prior networking knowledge. The course starts at the cable

Course content

69 lessons · 6h 28m

About the creator

Classytic