Hi list, Are there any way to check validity of MAC address but one times only and not every time while processing the virtual site ? Actually I used this : authorize { if (!Calling-Station-Id == "%{sql:SELECT mac_address FROM `mac` WHERE mac_address='%{Calling-Station-Id}'}") { update reply { Reply-Message += "MAC address %{Calling-Station-Id} was not found in database - Login refused " } reject } } The cache module is the only way ? Thanks. Nicolas.