Network commands

Twenty-two of the 43 commands. They divide by the layer you are suspicious of.

If you suspect	Start at
The site is not advertising or learning routes	BGP
The tunnel to the regional edge is down	IPsec
Traffic arrives but is discarded	Drop statistics
A specific connection behaves oddly	Flow table
Forwarding is wrong for a whole prefix	Routes and next hops
An interface is down or misconfigured	Interfaces
Name resolution	dig
Reachability off the node	cURL
Sockets and listeners	netstat
Clock skew breaking certificates or auth	chronyc-sources

The data plane is Argo, and it keeps its own forwarding state separate from the Linux kernel’s. ip shows you what Linux believes; rt, nh and vif show you what actually forwards traffic. When those two disagree, the data plane wins.