Cisco Certified Network Associate (CCNA) Practice Exam

If the line status is down and the protocol status is up, what could be the issue?

1. Layer 1 issue

2. Layer 2 issue

3. Configuration error

4. Protocol mismatch

The correct answer is: Layer 1 issue

In networking, the line status and protocol status provide valuable insights into the health of a network interface. When the line status reports as down while the protocol status indicates up, this often points to a physical layer issue. The line status reflects the physical connection and whether the interface is able to transmit and receive signals. If it's down, it suggests that there may be problems with the physical link, such as faulty cables, connectors, or hardware. This could include issues related to transceivers or network interface cards themselves. On the other hand, the protocol status being up indicates that the data link layer (Layer 2) is functioning at least theoretically, meaning that if there were a proper physical connection, the device would be able to establish a working protocol. In this scenario, other types of problems such as configuration errors or protocol mismatches, which typically impact layer 2 operations, are less likely to be the source of the issue since those conditions usually result in both line and protocol statuses being down. Therefore, the most accurate interpretation of the scenario is that it is indeed a Layer 1 issue.