Tutorials & mental models.
Short, opinionated walk-throughs of the CCNA® topics that actually trip people up. New post every couple of weeks.
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- ccnasecurityacl
Cisco ACLs Explained — Implicit Deny, Wildcards, and the 10-Second ACL Read (CCNA)
Free CCNA-level tutorial on Cisco ACLs for US networking learners. Implicit deny, wildcard masks, in vs out direction, and how to read any ACL in 10 seconds.
Read post → - ccnaswitchingvlans
VLANs Explained — Trunks, Access Ports, Native VLANs (CCNA Tutorial)
Free CCNA-level VLAN tutorial for US networking learners. Trunks, access ports, 802.1Q tagging, and native VLAN gotchas — the mental model that makes it click in 15 minutes.
Read post → - ccnaroutingospf
OSPF in 12 Minutes — The Mental Model Before the Commands (CCNA)
How OSPF actually works — the LSDB, SPF, neighbors, DR/BDR — explained as a story before you write a single `router ospf 1`.
Read post → - ccnaswitchingtroubleshootingvlanstrunks
'My Trunk Won't Pass VLAN 20' — A 6-Step Debug Workflow (CCNA)
Step-by-step troubleshooting for the classic CCNA-lab moment when you've configured the trunk but VLAN 20 traffic isn't reaching the other switch.
Read post → - ccnacareercertifications
The Free Certificates to Earn Before Your CCNA
Free Cisco and cloud certificates that thicken a junior NetEng CV before you sit the paid CCNA exam — sequenced for someone starting from help-desk or community college.
Read post → - ccnasubnettingfundamentals
Subnetting in Your Head — The Magic-Number Trick (CCNA)
The one method that turns CCNA subnetting from 'do the binary math' into 'glance at the mask, subtract, done'. Worked examples for /27, /28, /22, /21.
Read post →