This is an example of no scrolling. Good for small pages, but if your page extends beyond the size of the i-frame - tough luck, you can't access the rest of the page.
This is an example of auto scrolling. Doesn't show a scrollbar if the page fits within the i-frame, but if your page extends beyond the size of the i-frame - you can scroll down the rest of the page. This one has frameborder set to no and border width/color set. The no-scroll one has a frameborder and border width/color set
This is an example of scrolling. A scrollbar shows up even if the info fits into the area.