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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- ccnaip-connectivityinter-vlan-routingsvi
Inter-VLAN Routing — Layer 3 Switch SVIs vs Router-on-a-Stick (CCNA Tutorial)
Free CCNA-level inter-VLAN routing tutorial for US networking learners. Why VLANs can't talk by default, router-on-a-stick with dot1Q sub-interfaces, the Layer-3 switch SVI method real networks use, and the #1 mistake that leaves SVIs up but routing dead.
Read post → - ccnaip-servicesdhcpdora
DHCP Explained — DORA, Scopes, and the ip helper-address Relay (CCNA Tutorial)
Free CCNA-level DHCP tutorial for US networking learners. The DORA exchange step by step, why every message is a broadcast, the Cisco IOS server config, ip helper-address relay across subnets, and the show commands that prove leases are landing.
Read post → - ccnaccnpsecuritydhcp-snoopingdynamic-arp-inspectionip-source-guard
Layer 2 Security Explained — DHCP Snooping, Dynamic ARP Inspection & IP Source Guard (CCNA/CCNP)
Free tutorial on Cisco access-layer security for US networking learners. How DHCP snooping, Dynamic ARP Inspection (DAI), IP Source Guard, port security and 802.1x stack together to lock down the switch port — with the config and show commands.
Read post → - ccnaip-servicesnatpat
NAT & PAT Explained — Inside Local, Inside Global, and Overload (CCNA Tutorial)
Free CCNA-level NAT and PAT tutorial for US networking learners. Static vs dynamic vs PAT/overload, the four inside/outside local/global terms decoded, the config, and the show commands that prove it works.
Read post → - ccnaexamccna-v2
CCNA® v2.0 (2027): What's Changing in the 200-301 Exam — and Whether It Affects You
Cisco announced the CCNA 200-301 v2.0 blueprint. Here's what changed — a new AI section, a big shift toward configuration and troubleshooting, six domains down to five — when it goes live (Feb 3, 2027), and which version you should actually study based on your exam date.
Read post → - 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.
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