HANDS-ON NETWORK TROUBLESHOOTING

Learn Networking
By Fixing It.

Skip the subnet charts. You get a broken network, real commands to fix it, and a flag to capture once it works. Nothing to install.

Fix Your First Network

lab01 ~ ghost_in_the_gateway

pc-a:~$ ping 10.0.0.2
From 192.168.1.10: Destination Host Unreachable
pc-a:~$ ip route default via 192.168.1.1
pc-a:~$ ping 10.0.0.2
64 bytes from 10.0.0.2: ttl=62 time=1.4ms
✔ TASK COMPLETE  +50 XP

Reading about networks is not enough.

Watching videos feels like learning, until a real network breaks and you freeze. Fixing one is how it sticks.

Stop reading. Start doing.

Everything you need to go from your first ping to a routed network.

INSTANT ACCESSReal Terminals In Your Browser

No installs, no hardware, no setup. Open a lab, type real commands, and watch each ping travel across the network.

50 labs, one path

From your first ping to a routed network built on a blank router.

Track 1 · Network Basics

Hello, Network · IP addressing on one LAN
Link Lights · Layer 1: link status
Dead Ports · Several faults at once
Mask Mix-up · Subnet masks
Challenge: Office Wake-Up · Link lights, IPs and masks together
Who Owns This MAC? · ARP and MAC addresses
Twin Addresses · Duplicate IPs
Subnet Detective · Network and broadcast addresses
Two Switches · A bigger LAN
Challenge: Two Closets · Faults across two switches
Special Addresses · Private, loopback and APIPA
Challenge: Subnet Surgery · Masks that disagree
Challenge: Switch Closet Mystery · Duplicate IPs, stale ARP, dead link

Track 2 · Getting Off the LAN

The Way Out · Default gateway and routers
Lost Router · When the gateway link is down
Where’s My Address? · DHCP
Name Trouble · DNS
Open Ports · TCP, UDP and services
Web Detective · DNS and ports together
Two LANs, One Router · Gateways on both sides
Names Across Networks · DNS through a router
Port Numbers · Well-known ports
Challenge: Branch Office · Gateway, DNS and ports
Challenge: Lost in Translation · DHCP then DNS
Challenge: Shop Is Down · Gateway, DNS and ports together

Track 3 · Switching & Routing

VLAN Walls · VLANs
Two Departments · A bigger VLAN design
Static Routes · Routing tables
Gateway of Last Resort · Default routes
Three Hops · Routing across three routers
Challenge: Missing Routes · Static routes across three routers

Track 4 · Security & Troubleshooting

Block That Traffic · ACLs and rule order
Guest Wi-Fi · Rule order with three hosts
Challenge: Firewall Fiasco · ACL order plus a service fault
Challenge: Boss Lab: Triple Fault · Three faults, no hand-holding
Challenge: Final Boss: Datacenter Down · Five faults, six devices

Track 5 · Configure It Yourself

Blank Router · IOS modes and interface setup
Build the Gateway · Two routers and static routes
Trunk Lines · Access and trunk ports
Allowed on the Trunk · Trunk allowed VLAN list
Pick the Root Bridge · Spanning tree and root election
Challenge: Trunk Trouble · VLANs, access ports and trunks
DHCP on the Router · Router as a DHCP server
Hide Behind One Address · NAT overload
Let OSPF Do It · Dynamic routing
Default Route on a Router · Cisco default route
Read the Routing Table · Interface and route checks
Challenge: Routers Gone Quiet · Ports, addresses and static routes
Lock the Doors · Port security and SSH
Challenge: Full Build · Build a network from blank

You've read enough.
Now fix a network.

Just you, a broken network, and a flag to capture.

Instant browser terminal, zero setup
Guided labs with real commands
Earn XP and build skills that stick