CCNA study guide
CCNA · Work through your exam, one topic at a time.
The Cisco Certified Network Associate (CCNA) is Cisco's associate-level networking certification and the usual entry point into Cisco's certification path. It suits people who want proof of practical, day-to-day networking skill rather than product-specific depth: helpdesk and NOC staff moving into network roles, career changers coming out of a networking course, and junior engineers who already touch routers and switches and want a structured, vendor-recognized credential to show for it. The CCNA study guide has 6 sections and about 1,837 words.
01Network Fundamentals
Move fluently between the OSI seven-layer model and the four-layer TCP/IP model. The transport layer adds TCP or UDP headers (segments/datagrams), the internet layer adds IP headers (packets), and the data link layer wraps everything in an Ethernet frame with MAC addresses and an FCS trailer.
293 words, about 1 min02Network Access
Access ports carry one VLAN; trunk ports carry many using 802.1Q tags. The native VLAN is sent untagged, so both ends must agree - a native VLAN mismatch shows up in CDP/LLDP output and is a classic exam scenario.
321 words, about 2 min03IP Connectivity
Each entry has a prefix, next hop or exit interface, administrative distance (AD), and metric. The router forwards on longest prefix match first; AD and metric only break ties between identical prefixes.
289 words, about 1 min04IP Services
DORA: Discover (broadcast), Offer, Request (broadcast), Acknowledge. When the server sits on another subnet, the client-facing interface needs ip helper-address, which converts the broadcast into unicast to the server.
317 words, about 2 min05Security Fundamentals
Separate vulnerability (a weakness), exploit (the method that abuses it), and threat (a potential actor or event). Mitigations map to confidentiality, integrity, and availability.
317 words, about 2 min06Automation and Programmability
Traditional networking configures each device by CLI and runs distributed control planes. Controller-based networking centralises the control plane: Catalyst Center (formerly DNA Center) for campus fabrics, SD-WAN Manager for WAN.
300 words, about 2 min