Confusion about Undo keybinding

[Kevin Havener]

According to the tutorial and other places, undo is bound by default to 
C-/, C-_, and C-x u.  However in my newly installed emacs 24.5, C-/ is 
bound to DEL (backspace).  I don't think I have any .emacs type file 
overriding the defaults, so is this wrong or is the documentation wrong?

Wait just a minute.  C-/ is bound to undo in graphical mode and in xterm 
(-nw) mode.  C-/ is bound to DEL in my linux virtual consoles.  How is 
this possible?

Can you tell me what is going on?

Thank you,
Kevin Havener