mount: mount is, of course, a fundamental command. But don’t use in “ls mode” to list the current mounts. You’ll get a lot of gibberish, and the command is not designed for that.

Use findmnt instead.

nslookup is deprecated – or almost.

Use host for simple things, and dig for more information.

Notice, however, that all these commands query the DNS directly, instead of going through /etc/nsswitch.conf and /etc/hosts (as the programs that ask use the OS system calls will). If you want a “real” ip resolver, use either getent hosts [IP/NAME] or resolveip (the later comes with the msyql server!).

You should quit using ifconfig.

Get used to ip,  it’s much better.