Connection tracking (conntrack) is a feature that enables RouterOS to monitor and manage the state of all network connections passing through the router. It is essential for features like NAT, stateful firewalling, and proper use of mangle and filter rules.
MTCNA Course Material - Connection Tracking:
"Most firewall and NAT functionality depends on connection tracking being enabled. Without connection tracking, many features (like NAT) won't function properly." Rene Meneses MTCNA Study Guide - Firewall Section:
"Connection tracking is required for NAT and most firewall filters. When disabled, connection-state-based filtering or NAT is not possible." Terry Combs MTCNA Notes - Conntrack Section:
"Conntrack must be enabled to use full firewall capabilities, including NAT and filtering by connection states like established and related." Option A is partially true but not complete.
Option B is incorrect - conntrack may increase CPU load due to session tracking.
Option C is incorrect - mangle rules often depend on connection marks which require conntrack.
Only Option D accurately captures the critical requirement of connection tracking.