I have recently got a RB750GL. I decided as a temporary measure to stop users in my network accessing facebook to set a static dns entry to 192.168.0.2. I have since removed that and setup web proxy.
When I try resolve www.facebook.com I still get 192.168.0.2 instead of its proper Ip address. I have tried rebooting / shutting down my mikrotik with no luck. It still keeps resolving to that old IP. Current ROS is 5.7 with firmware 2.36.