is some one trying to send 404 request to attack my site?

I am getting lots of these ........


Fri Nov 15 09:02:21 2002] [error] [client 66.220.11.86] File does not
exist: /home/userid/public_html/404.shtml
[Fri Nov 15 09:02:21 2002] [error] [client 66.220.11.86] File does not
exist: /home/userid/public_html/scripts/..%2f../winnt/system32/cmd.exe
[Fri Nov 15 09:02:21 2002] [error] [client 66.220.11.86] File does not
exist: /home/userid/public_html/404.shtml


Thanks

I found the reason.