Cognos 10 distributed environment

I have installed the cognos in distributed environment. two content manger instance and 4 dispatcher instances… In the content manager instance configuration, i need to give the internal dispatcher uri and the external dispatcher uri…which one do i need to give there?? if i give any particular dispatcher uri, then if that dispatcher is stopped , then the system will work or not?

i have given the CM URI there (http://localhost:9300/p2pd/servlet/dispatch)

instead of the dispatcher uri (http://localhost:9100/p2pd/servlet/dispatch) and it is working fine… is this the correct setting???