Free guides that explain networking concepts from scratch. Animated diagrams, real-world examples, and hands-on labs.
Learn how IP addresses and subnet masks work using an apartment building analogy. Covers /24, /16, /8, and CIDR notation.
The internet's phone book — how domain names get translated to IP addresses. A records, TTL, resolvers explained.
How devices get IP addresses automatically — the hotel check-in analogy. DORA process, pools, and leases.
How your router shares one public IP among all your devices. SNAT, DNAT, port forwarding explained simply.
Split one switch into separate networks — like giving departments their own private floor. Access, trunk, tagging.
Your network's security guard — checking every packet against rules. Allow, deny, priority, stateful vs stateless.
All seven layers explained with a postal-system analogy — what each layer does and which devices live where. Interactive layer explorer.
Reliable courier vs fast postcard — when to use each transport protocol, with a side-by-side delivery race demo.
Why we ran out of IPv4 addresses and how IPv6 fixes it — notation, :: compression, and a live address inspector.
The burned-in hardware address — OUI vs device bits, unicast vs multicast, broadcast, decoded live in your browser.
How your device decides local vs remote and when it hands packets to the router — with a same-subnet decision tool.
RFC 1918, CGNAT, APIPA — why every home uses 192.168.x.x, with an instant private-or-public IP classifier.
How one IP runs many services at once — well-known ports, the connection 4-tuple, and a port lookup tool.
When to use each routing protocol — OSPF for inside your network, BGP for connecting to the internet.
Label switching explained with a package delivery analogy. Push, swap, pop — how ISPs forward millions of packets.
How routers forward packets using routing tables. Default routes, next hops, and longest prefix match.
How the internet glues together — AS numbers, peering, path selection, and multi-homing.
Areas, costs, SPF algorithm, neighbor states, and convergence — OSPF internals explained.
How carriers connect enterprise branch offices — VRFs, route targets, and label stacking.
SYN, SYN-ACK, ACK — watch a TCP connection set up step by step with real sequence numbers and connection states.
Priority lanes for voice and video — classification, marking, queues, and a hands-on congestion simulator.
Per-interface traffic filtering — how ACLs control what enters and leaves each router port.
Never trust, always verify — microsegmentation and least-privilege access between every service.
How VPN tunnels work — encryption, IPsec phases, site-to-site vs remote access.
The padlock explained — how HTTPS authenticates a site and agrees on a secret key, stepped through with forward secrecy.
Who's hidden, who's protected — forward proxies front clients, reverse proxies front servers, with a toggle diagram.
The systematic 5-step approach to diagnosing any network problem. From physical layer up.
A classic networking question — why ping works but your browser doesn't. Diagnostic flowchart included.
Why downloads fail but ping works — MTU black holes, PMTUD, and how to fix them.
When packets bounce forever — how TTL saves the day and how to spot loops in traceroute.
Forward path works, return path breaks — how asymmetric routing defeats stateful firewalls.
Map every hop to a destination — how TTL reveals each router, and why you see * * * timeouts. Includes a simulator.
How traffic gets distributed across multiple servers — round-robin, health checks, and VIPs.
How pods talk to services — ClusterIP, NodePort, Ingress, and CNI plugins demystified.
Bridge, host, and overlay networks — how containers connect to each other and the outside world.
Subnets, security groups, NACLs, route tables, and NAT gateways — AWS networking in plain English, with a build-a-VPC widget.
Content delivery networks — caching at the edge, cache hit vs miss, and how a request reaches the nearest PoP.
Same IP, multiple locations — how DNS root servers and CDNs route you to the nearest site, with built-in failover.
Software-defined networking — separating the brain (control plane) from the muscle (data plane). Program a flow in an interactive demo.
A smart GPS for company traffic — app-aware path selection across MPLS, broadband, and LTE, with an interactive failover demo.
MAC address tables, broadcast domains, and how switches decide where to send each frame.
How STP prevents broadcast storms — root bridges, port states, and convergence.
How devices discover each other's hardware addresses on a LAN — the ARP handshake.
Star, bus, ring, mesh — network floor plans compared, with a cut-a-link failure simulator for each design.
Stretch Layer 2 across Layer 3 with MAC-in-UDP — VNI, VTEP, overlay vs underlay, built packet by packet.
One-to-one, one-to-all, one-to-group — three delivery modes animated side by side, with an efficiency counter.
What actually happens when you connect to WiFi — your router, NAT, DHCP, DNS all working together.
Host a Minecraft server from home — DNAT, dynamic DNS, and firewall rules step by step.
From 10-person startup to 500-person enterprise — network architecture decisions that matter.
Dual uplinks, failover, and high availability — designing networks that survive failures.
No guides match your search. Try different keywords, or explore the labs directly.
Most of the fundamentals above have a hands-on lab in natted.cloud: subnets, switching, VLANs, routing, OSPF, BGP, MPLS, firewalls, NAT and DNS. Build real networks, trace packets hop by hop, and see how things break.
Open Lab →