Which CLI command allows administrators to troubleshoot Layer 2 issues, such as an IP address conflict?

The get system arp command is used to display the FortiGate's Address Resolution Protocol (ARP) table. The ARP table maps Layer 3 (IP) addresses to their corresponding Layer 2 (MAC) addresses. An IP address conflict occurs when two or more devices on the same network segment are assigned the same IP address. This conflict can be identified by examining the ARP table, where a single IP address might be associated with multiple or flapping MAC addresses. Therefore, this command is a primary tool for troubleshooting such Layer 2 issues.

A. get system status: This command provides general system information like firmware version, serial number, and license status, not specific Layer 2 networking data.

B. diagnose sys top: This command displays real-time system process and resource utilization (CPU, memory), used for performance troubleshooting, not Layer 2 issues.

C. get system performance status: This command shows a summary of performance statistics, such as active sessions and resource usage, not the ARP table.

1. Fortinet FortiOS 7.0.1 CLI Reference:

Page 1910

get system arp: The documentation explicitly states this command is used to "Display the system ARP table." The ARP table is fundamental for diagnosing Layer 2 to Layer 3 mapping issues like IP conflicts.

Page 2011

get system status: Described as "Display system status

" confirming its use for general information.

Page 1018

diagnose sys top: Described as "Display real-time process information

" confirming its use for system performance monitoring.

Page 1986

get system performance status: Described as "Display system performance statistics

" confirming its use for high-level performance metrics.

2. Fortinet FortiOS Handbook 7.0.0 - Troubleshooting:

Section: Troubleshooting tools

Page 13: In the context of network troubleshooting

the guide explains

"An IP conflict occurs when two devices on a network are assigned the same IP address... You can use the ARP table on the FortiGate to help identify the conflicting devices." This directly links the troubleshooting of IP conflicts to the use of the ARP table

which is accessed via get system arp.