I registered a free web hosting at http://www.zymic.com/.

In fact, I develop an Internet family tree generation system where
users could register and build their own family tree. The main family
tree page is formed using multiple HTTP requests - to draw lines
between persons and to load photos. Thus, these requests are made from
the single HTML page (main family tree page) in the form of URIs from
HTML code.

When I connect to Internet via modem (slow bandwidth), all is ok. But
when the bandwidth is high, I see the following problem. Some lines
and photos are successfully loaded into browser while the rest of them
are not. Sometimes the page cannot load at all, showing "403
Forbidden!" page.

I suspect that there is some limitation preventing DDOS attack or
something... But what could be the solution?