Where is the Internal IP address stored in Ubuntu?

Question

Is there some file in the Linux-Ubuntu filesystem that contains the internal IP of the machine running it? Ideally, is the output provided by the following command

hostname -I

saved somewhere in the filesystem?

(thanks to How do I find my internal ip address?)

Answer 1

You can find a tree in /proc/net/fib_trie

Otherwise you can look it up with a tool such as ip addr