When i configure hotspot and if a user is surfing then the ping of dns goes high. Can somebody help me how to bypass icmp packets through hotspot, so that if the user is utilising the full allocated bandwidth then also all the ping request will be normal.
It sounds like the pings are “normal”. The more bandwidth the users require, the longer it will take for all other traffic, not just icmp. You can set priority on certain types of traffic, but that is out of my field of expertise. The docs cover this here: http://www.mikrotik.com/testdocs/ros/2.9/root/queue.php
If you are referring to wireless bandwidth throttling by the hotspot, it knows nothing of packet types. If you throttle a wireless client to 512K, then all the traffic generated by that client, including pings, must share that 512K. If the web browser is already using 512K, the ping request will be delayed until there is bandwidth available.
If you want to throttle the users later with simple queues and traffic priority, then see the link above.