Ping Labz

BGP looking glasses explained: what they show, the public servers worth bookmarking, a four-step troubleshooting recipe, and how to host your own with hyperglass.

All 8 OSPF neighbor states (Down, Attempt, Init, 2-Way, ExStart, Exchange, Loading, Full), what triggers each transition, and what to check when a neighbor is stuck.

VLAN, subnet, and broadcast domain are not the same thing. The layer each lives at, the relationships between them, and the misalignment that breaks hosts silently.