Dynamic lists are assigned to contacts based on the conditions you specify. These conditions will work for existing or new contacts alike and will automatically assign the qualifying contacts to the Dynamic List.
These lists automatically update their contacts based on the criteria that is set.
Contacts will join the list when they meet the criteria and leave the list when they no longer meet the criteria. This is considered to be one of the smart lists.
This ensures that the list you are sending the survey is always updated with new contacts and correct contacts who meet the criteria.