AAA 4.1 error :

Hi,

I would like to specify the problem I am facing while accessing ACS 4.1 through a switch or router, We have a appliance for ACS – 1113 SE, I have configured aaa commands and added the router and switch as AAA Client in ACS. I get an error while I am trying to authentication a user in ACS , No authoritative response from any server, even though ACS is reachable to switch and router, I get the above error,

Kindly help ??