Hi every one
there is a upload center that it's files are divided between two servers.
one of the servers is located in Washington and other one is located
in New York.
so some files will be downloaded from Washington server and other files will be downloaded from New York server.
and i don't know name of the files.
and i want to use one domain for both of them.
for example :
mehdiali/files/a.exe (it is downloaded from Washington server)
mehdiali/files/b.exe (it is downloaded from New York server)

thank you in advance.

What is your exact question? Are you wanting to know how to set something like this up? This seems more like a programming issue. What type of front end? What language is used? Your gonna need to spill out a lot more information than the generic question you've asked.

thank you for your replies,
the solution :
the user type mehdiali/files/b.exe(requested_url) that isn't available in server A.
so i must redirect it to server B.
i write a command like this in htaccess file :

ErrorDocument 404 "http://localhost/divider.php?r_u=requested_url"

so in divider.php page i have $HTTP_GET_VARS['r_u']
and after fetching the b.exe(file name)
i'll redirect it to server B, like this :
header("location:mehdiali2/filename/b.exe");

but my problem is how i can find requested_url.
what do you write instead of requested_url in
ErrorDocument 404 "http://localhost/divider.php?r_u=requested_url"
is there any variable?

i don't know the name of the files.
please send the complete code.