Here is what you learned:
Fundamentals: Latency, jitter, loss affect applications differently. Real-time needs guarantees.
Marking: DSCP at Layer . CoS at Layer . Trust boundaries control markings.
Queuing: FIFO treats all equally. Priority serves high first. WFQ shares proportionally. LLQ combines both.
Congestion: Tail drop causes synchronization. RED drops early. WRED differentiates by class.
Shaping vs policing: Shaping buffers. Policing drops.
Models: IntServ reserves per-flow. DiffServ uses per-hop behaviors.
Voice/video: Voice needs ms with EF. Video needs bandwidth with AF41.