If you’re interested in a really good cheat sheet for QoS, PacketLife has some great ones. It will save you from looking dumb when your brain decides to take a holiday.
It containins information on:
Quality of Service Models
Layer 2 QoS Markings
IP QoS Markings
QoS Flowchart
QoS Terminology
Per-Hop Behaviors
Congestion Avoidance
IP Type of Service (TOS)
Precedence Values
DSCP Values
Queuing Comparison Chart
First In First Out (FIFO)
Priority Queuing (PQ)
LLQ Configuration Example
Custom Queuing (CQ)
Weighted Fair Queuing (WFQ)
Class-Based WFQ (CBWFQ)
Low Latency Queuing (LLQ)
Troubleshooting QoS
Update
As Packetlife is down, I’ve linked them to wayback machine.
https://web.archive.org/web/20240809085825/https://packetlife.net/library/cheat-sheets/