Study paths
Choose a focus area and work through its labs in order. Track what you’ve completed and pick up where you left off.
Network engineer foundations
Practice the routing and access-control portion of a network engineering interview. Follow a packet, narrow the fault, make a minimal change, and verify the return path.
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Follow the packet
Use route tables and traces to distinguish a missing route, a discard route, and a loop.
Check both directions
Prove the forward path and the return path; preserve traffic that must remain blocked.
Restore the control plane
Inspect configuration and protocol state before changing OSPF or BGP.
Transfer the method
Apply the same investigation to a different incident, without copying a remembered fix.
Operate a multi-service network
Separate host-specific failures, incomplete repairs, and wrong-branch forwarding while keeping the other services online.
Troubleshoot across network environments
Apply the method to campus, branch, data-center, monitoring, service-edge, backup, industrial, and remote-access layouts.