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Troubleshooting practice labs — Page 3

59 hands-on Troubleshooting scenarios you build in your own Cisco Modeling Labs instance and grade against the answer key. Troubleshooting configuration and troubleshooting practice for CCNA and CCNP.

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BeginnerFree2026-06-25

CCNA Static Routing: Bidirectional End-to-End Connectivity

Hands-on CCNA static routing lab: build a small hub-and-spoke with two stub routers and a hub router. Configure default routes on the spokes and specific static routes on the hub so two user LANs reach each other end-to-end. Validate from real hosts and practice first-hop and return-path troubleshooting.

CCNA45 min5 objectives

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IntermediateLocked

CCNA Static Routes: Manual Summarization

Hands-on CCNA static routing and manual summarization lab using a compact HQ–Branch–Remote topology. You will replace three specific static routes to Branch networks with a single /22 summary at HQ, verify end-to-end host reachability, observe the routing table reduction, and prevent over-aggregation loops by adding a Null0 discard route at Branch. A recommended step has you add the same /22 summary at Remote (replacing its default) to practice summarization on both sides.

CCNA55 min6 objectives

IntermediateLocked

OSPF Cost & Path Selection: Deterministic Control (3 Routers)

Build a 3-router triangle with two end-to-end paths between Branch A and the Data Center. Stand up OSPF area 0, create an ECMP condition, then intentionally steer traffic using ip ospf cost. Verify from the end hosts and troubleshoot common OSPF control-plane mismatches.

CCNA55 min5 objectives

AdvancedLocked

OSPF MD5 Authentication: Backbone Integrity and Area Mismatch

Deploy OSPFv2 with MD5 authentication on backbone links, deliberately trigger and diagnose an area mismatch adjacency failure, then fix it and restore end-to-end reachability between two branch hosts in a compact three-router topology.

CCNA & CCNP68 min5 objectives

IntermediateLocked

OSPF Multi-Area: ABR Area Mismatch and Route Repair

Build and troubleshoot a compact multi-area OSPF design with a single ABR between area 0 and area 10. You will deploy OSPF, observe an adjacency failure caused by an area mismatch on one transit link, repair it, and validate that routes propagate end to end between two user LANs.

CCNA & CCNP55 min4 objectives

BeginnerDailyLocked

Layer 2 Access Hardening: PortFast, BPDU Guard & Sticky MAC

Hands-on CCNA Layer 2 switching lab: build VLANs, access ports, hardened 802.1Q trunks, and basic port-security across two access switches and an L2 core. Verify segmentation end-to-end from real hosts and practice troubleshooting native-VLAN and port/VLAN mismatches.

CCNA55 min5 objectives

BeginnerFree2026-06-23

OSPFv2 Single-Area Fundamentals: Adjacency and Area 0 Basics

Hands-on CCNA beginner lab: build a 3-router chain with end hosts, enable OSPFv2 area 0, form full adjacencies, advertise loopbacks and LANs, verify route propagation end-to-end, and intentionally create then resolve an OSPF area mismatch on a transit segment.

CCNA55 min5 objectives

Free with an account

AdvancedLocked

OSPFv2 Multi-Area Capstone: 3-Rtr Line, Auth, LAN Host Intact

Advanced CCNP OSPFv2 multi-area capstone. Build a three-router line topology with area 10 at the branch, area 0 at the core, and MD5 authentication on the area 0 transit. Advertise all loopbacks and a branch user LAN. Validate end-to-end reachability from the branch host to every router loopback and the core LAN. Includes realistic enterprise management and verification flows.

CCNA & CCNP80 min4 objectives

BeginnerLocked

OSPFv2: Router IDs, Neighbor States, and Loopback Adjacency

Deploy OSPFv2 across three routers with unique, loopback-derived router-ids. Observe OSPF neighbor state transitions, advertise loopbacks and LANs, and troubleshoot an adjacency failure caused by a duplicate router-id. Validate full end-to-end reachability from client hosts after fixing the issue.

CCNA55 min5 objectives

IntermediateLocked

CCNA: OSPF Passive Interfaces & Default Origination

Deploy OSPFv2 across a 3-router, 2-LAN branch/core/edge topology. Mark LAN-facing interfaces as passive so they do not send OSPF hellos or form adjacencies. Originate a default route only from the edge router and verify default propagation end-to-end using real client traffic. Includes realistic troubleshooting around missing adjacencies, non-propagating defaults, and unreachable external destinations.

CCNA70 min5 objectives

AdvancedDailyLocked

CCNP: OSPF Backbone & Area Mismatch Recovery

Advanced multi-area OSPF lab with a realistic two-site design and a WAN ABR. You will deploy OSPF with a backbone (area 0) and a non-backbone area, intentionally create an area mismatch on one transit link to observe the failure, then correct it to restore full reachability. The final build demonstrates solid OSPF hygiene and SSH-only management.

CCNP85 min5 objectives

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