The central problem
Keep messages moving.
Good network reasoning separates the mechanism from the symptom. Start with the boundary, identify the evidence, and test the explanation that accounts for the observation.
One signal rarely proves the whole path.Compare observations from the relevant layer before changing a configuration.
Build the model
Four useful signals
Opening handshake
Negotiates the transition from HTTP.
Persistent channel
Keeps one connection available.
Bidirectional messages
Lets either endpoint send updates.
Heartbeat
Detects a broken or idle connection.
Mini investigation
Inspect the evidence
Select the observation and identify the most direct next check.
NEXT CHECKDirect evidence
This observation narrows the mechanism but does not prove every downstream layer.
Compare it with one nearby-layer check.
Knowledge check
Test your model
Answer five questions.