This object indicates whether the optional heartbeat mechanism is active for one specific remote address of this association. Heartbeats on a given path are how SCTP proactively confirms an otherwise idle secondary path is still alive before it is actually needed for failover; a flag showing inactive for a backup path means that path's health is not being actively verified, so a failure there might not be detected until failover is actually attempted. Disabling heartbeat on a rarely used backup address to save CPU means that path's real availability during an actual primary-path failure is essentially untested until the moment it is needed.