How to reverse column order of a file in Linux from the command line

Question

I have a file named ip-list with two columns:

IP1    Server1
IP2    Server2

And I want to produce:

Answer 1

More than two columns

printf "\
1 2 3 4
5 6 7 8
" | awk '{for(i=NF;i>0;i--)printf "%s ",$i;print ""}'

Output:

4 3 2 1
8 7 6 5

See also: https://unix.stackexchange.com/questions/46275/swapping-an-unlimited-number-of-columns

Tested in GNU Awk 4.0.1.