[ams6110]

They're a bit dated. Use dig instead of nslookup, and right from the ifconfig man page:

NOTE

This program is obsolete! For replacement check ip addr and ip link. For statistics use ip -s link.

[blhack]

Where does it say that?

http://www.openbsd.org/cgi-bin/man.cgi?query=ifconfig

Pedantry, but keep in mind that there isn't really "the" man page for this.

Ubuntu might want to deprecate ifconfig, but that doesn't mean everyone does.

[ams6110]

You're right, and I use OpenBSD myself so I should have qualified it. The man page I quoted was CentOS in this case.

[protomyth]

This is Linux specific advice for ifconfig, correct?

[ams6110]

Yes