Networking / Stage 2 of 14

How Linux picks a route

Not running Starting usually ~20 s

Step 7 of 7 · summary · 2 min

Summary

A route is a line of the table: the destination network, the gateway after via and the interface after dev.
The kernel adds the route to its own subnet by itself; other networks need lines of their own or default.
Of the matching lines, the longest prefix wins; the metric only decides between equal prefixes.
ip route get shows the kernel's decision, and ping shows that the exchange worked.
At the start of the lesson 198.51.100.20 did not answer: the client knew only its own subnet 192.0.2.0/24 and had no route to that address.

Ubuntu 24.04