This document outlines the key topics covered in the CCNA 1-4 certification courses. CCNA 1 introduces fundamental networking concepts including protocols, addressing, Ethernet, and basic router and switch configurations. CCNA 2 covers switching technologies, routing protocols, VLANs, ACLs, DHCP, DNS, and NAT. CCNA 3 focuses on advanced switching technologies, first-hop redundancy protocols, wireless networking, and routing protocols. CCNA 4 examines WAN technologies, VPNs, tunneling, NAT, syslog, SNMP, NetFlow, and network architecture.