Legacy and modern protocols alike underpin communication within local networks, and this episode brings together three foundational ones: CSMA/CD, ARP, and Neighbor Discovery. We begin with CSMA/CD, once crucial in shared Ethernet environments, explaining how devices listened before transmitting and how collisions were handled. Although largely obsolete due to switched networks, CSMA/CD still appears on the exam and helps illustrate Ethernet history.

We then shift to ARP (Address Resolution Protocol), which maps IP addresses to MAC addresses in IPv4 networks, and ND (Neighbor Discovery), which performs a similar role in IPv6 environments. You'll learn how ARP tables are populated, how ARP spoofing works, and how ND leverages ICMPv6 to perform neighbor solicitation and router discovery. These are core networking concepts that you'll encounter often in both troubleshooting and exam content.