The PingLabz CCNA Labs library teaches you to build a network from a blank configuration. The Troubleshooting Labs do the inverse. You inherit a network that is already broken, you get a support ticket that describes a symptom and nothing else, and your job is to localize the fault and fix it. That is the single skill the CCNA 200-301 exam leans on hardest in its hands-on items, and the one most study material skips entirely.
Every lab in this series runs on the same five-node PingLabz CCNA Base Topology as the rest of the library, so it fits inside Cisco Modeling Labs Free. Each lab ships a downloadable topology that boots straight into its broken state, and every command output in every lab was captured from that topology running on Cisco IOS XE, broken on purpose and then fixed.
How the troubleshooting labs work
Each lab is a small ticket queue. You import the topology, start it, and work the tickets in order. A ticket gives you a symptom in the user's words and a single success criterion. It does not tell you the cause. You reproduce the symptom, climb the OSI stack until a command contradicts what you expect, fix it, and verify. After each ticket the lab shows the root cause and the exact fix, so you can check your work against real captures.
Because the topologies are small, faults can mask one another, exactly as they do on a real network. The method that beats this is always the same: work bottom-up, fix the lowest layer or most upstream problem first, and re-test before moving on.
The shared topology
Three routers (R1, R2, R3), one managed switch (SW1), one host (HOST1), and an unmanaged switch (SW2). R1 and R2 share the LAN 10.20.0.0/24 through SW1; R2 reaches R3 over the point-to-point link 10.30.30.0/30; each router carries a loopback. It is the same standardized IP scheme and the same pinglabz / PingLabz!23 credentials used across the whole library, so the addressing you learn in the build labs is the addressing you troubleshoot here.
The troubleshooting labs
Six labs, grouped by the five CCNA 200-301 exam pillars, plus a multi-fault capstone. The first is free with no signup; the rest are part of PingLabz Pro.
| Lab | Pillar | What you diagnose and fix | Access |
|---|---|---|---|
| ts-nf-01 Connectivity Tickets | Network Fundamentals | A shut interface, a dead static next-hop, and a wrong subnet mask. Reading U vs . in ping. | Free |
| ts-na-01 Switching and VLAN Tickets | Network Access | An access-VLAN mismatch, a typo'd auto-created VLAN, and an access port stuck in trunk mode. | Pro |
| ts-ipc-01 OSPF Tickets | IP Connectivity | An area mismatch, a passive interface, and a missing network statement. Adjacency-down vs route-missing. | Pro |
| ts-ips-01 DHCP and NAT Tickets | IP Services | A starved DHCP pool, a missing ip nat inside, and a NAT ACL matching the wrong subnet. | Pro |
| ts-sec-01 Security Tickets | Security Fundamentals | A reversed ACL, a port-security err-disable, and a VTY access-class lockout. | Pro |
| ts-cap-01 Capstone: Branch Outage | Mixed | One symptom, three stacked faults across L2, L3, and NAT. Bottom-up triage under pressure. | Pro |
Where this fits
The troubleshooting labs are the companion to the build labs. Configure a feature in the main labs library, then come here to practice fixing it when it breaks. If you want the general diagnostic method first, the build lab nf-11 Troubleshooting Layer Symptoms teaches the seven-step escalation drill that underpins this whole series. When you are ready to build an entire campus from scratch, sit the CCNA Mega Lab.
Frequently asked questions
Do I need a paid CML license?
No. Every troubleshooting lab is sized for the same five-node base topology and fits inside Cisco Modeling Labs Free. Import the lab's .yaml, start it, and it boots into the broken state.
Are the captures real?
Yes. Each fault was injected into a live Cisco IOS XE topology in CML, captured in its broken state, then fixed and captured again. The outputs you read are what you will see on your own screen.
How are these different from the build labs?
The build labs hand you a goal and a blank slate: configure VLANs, configure OSPF, configure NAT. The troubleshooting labs hand you a broken network and a ticket. Same topology, same IP scheme, opposite skill.
Which lab should I start with?
Start with the free ts-nf-01 Connectivity Tickets. It teaches the bottom-up method every other lab in the series relies on, then work up through the pillars to the capstone.
Ready to start? Open the free connectivity tickets lab, or sign up for Pro to unlock the full queue.