CCNA STUDY GUIDES_
Plain-English CCNA articles. No build-in-public stories, no personal essays — just the concepts, troubleshooting, and reference material you'd actually read while studying. Looking for chronological everything? See ARTICLES. Looking for free Packet Tracer lab files? See LABS.
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GUIDE
[ CCNA · OSPF · LSA TYPES ]
OSPF MULTI-AREA & LSA TYPES:
WHAT EACH LSA CARRIES Why OSPF carves the domain into areas, the four router roles (internal / backbone / ABR / ASBR), every CCNA-relevant LSA type (1, 2, 3, 4, 5, 7) with originator and flooding scope, and the five OSPF packet types tied to the adjacency state machine. GUIDE [ CCNA · IPV6 ] IPV6 FOR THE CCNA:
COMPRESSION, TYPES & EUI-64 The short IPv6 guide for the exam — 128-bit anatomy, the two compression rules, the six address types, and EUI-64 step-by-step. Paired with three free drill tools. GUIDE [ CCNA · ROUTING · OSPF ] OSPF EXPLAINED:
LINK-STATE ROUTING FOR THE CCNA No CLI — just the mental model. Distance-vector vs link-state, LSDB & SPF, areas, router-ID picking order, the process-ID trap, and wildcard masks. Read this before you touch the lab. GUIDE [ CCNA · OSPF · TROUBLESHOOTING ] OSPF ADJACENCY STATES:
WHY YOURS IS STUCK IN EXSTART Every OSPF state — DOWN, INIT, 2-WAY, EXSTART, EXCHANGE, FULL — and the one-line fix for each failure mode. MTU mismatch, one-way Hellos, flapping timers, and the troubleshooting decision tree. GUIDE [ NETWORKING · VPN · TROUBLESHOOTING ] THE 1500-BYTE LIE:
WHY YOUR VPN HANGS ON BIG FILES The VPN's up. Pings are 18ms. Web works. Then a 50MB download hangs at 4%. Here's the math, the captures, and the MSS-clamping fix — per platform. REFERENCE [ CCNA · REFERENCE ] SUBNETTING CHEAT SHEET:
CIDR, BLOCK SIZES & HOST COUNTS Every prefix /8 through /32 in one place. Subnet mask, block size, total addresses, usable hosts, and wildcard mask. Save the image or bookmark the page. GUIDE [ CCNA · SUBNETTING ] WHY SUBNETTING FINALLY
CLICKED FOR ME Three weeks of confusion. One diagram that changed everything. Here's the mental model that actually works — and why most guides start from the wrong end.
WHAT EACH LSA CARRIES Why OSPF carves the domain into areas, the four router roles (internal / backbone / ABR / ASBR), every CCNA-relevant LSA type (1, 2, 3, 4, 5, 7) with originator and flooding scope, and the five OSPF packet types tied to the adjacency state machine. GUIDE [ CCNA · IPV6 ] IPV6 FOR THE CCNA:
COMPRESSION, TYPES & EUI-64 The short IPv6 guide for the exam — 128-bit anatomy, the two compression rules, the six address types, and EUI-64 step-by-step. Paired with three free drill tools. GUIDE [ CCNA · ROUTING · OSPF ] OSPF EXPLAINED:
LINK-STATE ROUTING FOR THE CCNA No CLI — just the mental model. Distance-vector vs link-state, LSDB & SPF, areas, router-ID picking order, the process-ID trap, and wildcard masks. Read this before you touch the lab. GUIDE [ CCNA · OSPF · TROUBLESHOOTING ] OSPF ADJACENCY STATES:
WHY YOURS IS STUCK IN EXSTART Every OSPF state — DOWN, INIT, 2-WAY, EXSTART, EXCHANGE, FULL — and the one-line fix for each failure mode. MTU mismatch, one-way Hellos, flapping timers, and the troubleshooting decision tree. GUIDE [ NETWORKING · VPN · TROUBLESHOOTING ] THE 1500-BYTE LIE:
WHY YOUR VPN HANGS ON BIG FILES The VPN's up. Pings are 18ms. Web works. Then a 50MB download hangs at 4%. Here's the math, the captures, and the MSS-clamping fix — per platform. REFERENCE [ CCNA · REFERENCE ] SUBNETTING CHEAT SHEET:
CIDR, BLOCK SIZES & HOST COUNTS Every prefix /8 through /32 in one place. Subnet mask, block size, total addresses, usable hosts, and wildcard mask. Save the image or bookmark the page. GUIDE [ CCNA · SUBNETTING ] WHY SUBNETTING FINALLY
CLICKED FOR ME Three weeks of confusion. One diagram that changed everything. Here's the mental model that actually works — and why most guides start from the wrong end.