Mangle rules that mark routing (using the routing-mark property) can only be applied in the following chains:
prerouting: For traffic arriving at the router
output: For traffic generated by the router itself
Other chains like forward, input, postrouting do not support routing-mark.
A.✔Correct – prerouting and output are used for routing-mark
B.✘forward does not support routing-mark
C.✘forward is invalid for routing-mark
D.✘input does not support routing decisions
E.✘postrouting is used for NAT, not routing
Extract from MTCNA Course Material – Mangle and Routing Marks:
“Routing-mark is applied only in prerouting (for transit traffic) and output (for router-generated traffic).”
Extract from MikroTik Wiki – Mangle:
“routing-mark can be used only in prerouting and output chains.”
Extract from René Meneses Study Guide – Mangle and PBR:
“To perform policy-based routing, use prerouting or output to assign routing-marks.”
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