Link Layer Troubleshooting Questions

Troubleshooting at the link layer and local network segment. Topics include Address Resolution Protocol operation and neighbor tables, Media Access Control addressing and switch forwarding behavior, duplicate address detection and gratuitous neighbor announcements, spanning tree protocol related issues, duplex and speed negotiation failures, interface flapping, broadcast storms, and physical media faults. Candidates should know how to inspect neighbor and media access control tables, use link diagnostics such as ethtool, and capture link layer traffic to identify root causes.