sa php5 npr vrlo jednostavno...
PHP kôd:
$p = get_headers("http://www.google.com", 1);
if (preg_match("/200 OK/", $p[0]))
echo "page found";
else
echo "page NOT found";
ili...
http://www.google.com/search?q=php+check+url+for+404
ps. nisam bas neki entuzijasta ali ajde