1Network Fundamentals

• 1.1Network components and topologies

  Covers the roles of components such as the router, L2/L3 switches, next-generation firewall (NGFW), IPS, AP and WLC, endpoints, servers, and PoE; topologies such as 2-tier, 3-tier, and spine-leaf; SOHO and WAN; and on-premises vs. cloud—all as the design judgment of "which device or topology fits this requirement."

• 1.2The OSI and TCP/IP models and TCP/UDP

  Covers the correspondence between the layered OSI reference model and the practical TCP/IP model, encapsulation that wraps upper-layer data in lower-layer headers along with each layer's PDU, and TCP (reliable, three-way handshake) versus UDP (low-latency, connectionless) framed as the judgment of "which fits this application."

• 1.3Physical interfaces, cabling, and switching

  Covers choosing between copper (UTP) and optical fiber (SMF/MMF), straight-through/crossover and Auto-MDIX, and an L2 switch's core behavior—MAC address learning, aging, flooding, and the MAC address table—framed as the judgment/diagnosis of "which cable for a distance/speed" and "why frames leak to every port."

• 1.4IPv4 addressing and subnet design

  Covers the structure of IPv4 addresses, the private/public distinction, the subnet mask and CIDR, and VLSM, which splits space into variable-length blocks sized to the required host count—learned as the design judgment of "allocating a limited address space without waste," with manual verification.

• 1.5IPv6, wireless, and virtualization

  Covers 128-bit IPv6 address notation and types (GUA/ULA/link-local/multicast/anycast) and EUI-64, wireless fundamentals (2.4/5 GHz, non-overlapping channels 1/6/11, SSID, encryption), and virtualization (VM/container/VRF), framed as design and troubleshooting judgment.