The OSI model provides a framework for discussing network layers.
Layers (bottom to top):
. Physical: Cables, signals . Data Link: MAC addresses, switches . Network: IP addresses, routing . Transport: TCP/UDP, ports . Session: Connection management . Presentation: Encoding, encryption . Application: HTTP, DNS, SMTP
In practice: Layers - matter most for SRE. Layers - often blur together.
Interview tip: Be specific about layers. TLS sits at layers -. Load balancers can be L or L.