This read-only object reports which line monitoring method is active on a PPP link: none, keepalive (periodic echo probe), or LQM (Link Quality Monitoring which tracks frame discards and errors). It reflects the actual monitoring technique being used, which can be deduced from the keepalive period and quality thresholds configured on the link. Operators use this to verify which monitoring mode is protecting the PPP session and understand the detection sensitivity for link faults.