Cisco Certified Network Associate (CCNA) Practice Exam

What does the PPP LCP function called Link-Quality Monitoring (LQM) do?

1. Optimizes data flow

2. Monitors router bandwidth usage

3. Disables an interface exceeding error threshold

4. Establishes connections between protocols

The correct answer is: Disables an interface exceeding error threshold

The Link-Quality Monitoring (LQM) function within Point-to-Point Protocol (PPP) is designed to assess the quality of the link between two endpoints. Its primary role is to track error rates and link performance, ensuring that the communication link remains reliable. If the LQM detects that the error rate surpasses a defined threshold, it responds by taking action to maintain network stability and performance, specifically by disabling the interface. This minimizes the impact of a poor-quality link on the overall network operations, thereby enabling the network devices to avoid sending data over a failing link. By using LQM, network administrators can maintain a healthy network environment, as LQM helps proactively manage connections based on the detected quality of the link. This is crucial for maintaining efficient and reliable data transmissions in a network. Thus, the action of disabling an interface that exceeds the error threshold accurately captures the intent and function of LQM within PPP.