CCNA certification contains a lot of knowledge, mainly divided into the following eight areas: 1. Network basics: involves the introduction of basic concepts such as computer composition, data transmission methods, network devices, network topology, etc. 2. Routers and switches: learn how to configure routers and switches, how to manage and monitor routers and switches. 3. Network protocols: learn the basics of network protocols, such as IP, TCP, UDP, etc. It also requires knowledge of routing protocols such as RIP, OSPF, EIGRP, etc. 4. Network Management and Security: In network management, candidates need to know how to configure and manage network devices, how to manage and maintain the network, and how to solve network faults and security problems, etc. 5. Network Topologies: Learn how to select and design different network topologies, such as what cases to choose a WAN and LAN: Candidates need to know how enterprises connect through WAN and LAN, and at the same time, they need to understand how to configure and manage network devices such as routers, switches and firewalls.7. Network Address Translation: Learn how to translate between different IP address ranges.8. Wireless Network: Understand the working principle of wireless networks, composition, configuration and use and other related knowledge, as well as the security and management of wireless networks.