check SCREEN buffer in PUTTY terminal of linux

ISSUE:
scrollback on putty terminal of linux didn't display the output of screen command.

CAUSE:
the buffer from screen command is not synced with putty buffer.

SOLUTION:
type C-a (ALT-a ) [ to go to copy mode. Then move your cursor to scroll back to screen output buffer.
type escape to get out of copy mode.

DEFINE BUFFER SIZE:
screen -h 5000

reference:
http://www.samsarin.com/blog/2007/03/11/gnu-screen-working-with-the-scrollback-buffer/