Everything mapped to the CCNA 200-301 blueprint. Articles tagged CCNA cover the exam topics in the order you actually learn them, each one backed by a lab you can build yourself.
Static routing is the first routing you ever configure and the last routing you stop using. Dynamic protocols get the attention, but every real network still leans on hand-configured routes for default gateways, stub sites, backup paths, and steering
Ask a room of engineers "which route wins?" and most reach straight for administrative distance. That is the wrong first answer. Before a router ever looks at AD or metric, it applies longest prefix match: given a destination
Administrative distance ranks how much a router trusts each source of routing information, and it is the reason a prefix installs via EIGRP when you expected OSPF. Here is the complete default table, the floating static design that depends on it, and a real CML capture of the same prefix...
The routing table is the single most important piece of state on a Cisco router, and show ip route is the command you will type more than any other. Yet most people skim it: they look for the destination, glance
Every switch and router quietly announces itself to its directly connected neighbors, and you can read those announcements to map a network without a single diagram. Two protocols do this job: CDP, Cisco's own Discovery Protocol, and LLDP,
Half of "the network is down" tickets end at the client. Before touching a switch, verify four things on the host itself: its IP address and mask, its default gateway, its DNS servers, and whether it can reach
CCNA objective 1.12 asks for "virtualization fundamentals: server virtualization, containers, and VRFs" - three technologies that all answer the same question at different layers: how do you run multiple isolated things on one piece of hardware? Servers virtualize
Every access point, IP phone, and security camera on your network probably has no power cable. Power over Ethernet delivers DC power over the same twisted pair carrying data, and CCNA objective 1.3 expects you to know the concepts:
Three address blocks appear in virtually every network you will ever touch: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. They're defined in RFC 1918, they're the reason
Ask why a campus network has an "access layer" or why data centers abandoned the tree design entirely, and you're asking about topology architectures - CCNA exam objective 1.2 and, more usefully, the vocabulary every design
"The network is slow" tickets that turn out to be a duplex mismatch are a rite of passage. The link is up, pings work, and yet throughput is terrible and retransmissions are everywhere. This article shows you how
Every frame a switch forwards is a lookup in one table: the MAC address table (historically the CAM table). Understanding how entries get into that table, how long they stay, and what happens when a destination isn't in