DNC stand for "Do not Contact" or "Do not Call". Adding contacts to your system DNC will allow the system to scrub those numbers out of future campaigns so you don't accidentally contact someone that does not wish to hear from you again.
Start by going to "Phone system" in your menu, then click on "DNC".
DNC Numbers: Here you'll be able to search for your DNC numbers and click the track can icon if you even need to take them off, click on the blue addition symbol to add another number
DNC Area Codes: Add any area codes you'd like to completely avoid and delete things you change your mind about
DNC States: Add any states you'd like to completely avoid and delete things you change your mind about
DNC File upload: If you have a spreadsheet of multiple numbers you'd like to bring into the system - must be a CSV file - watch the video above to see how to convert an XLSX file to CSV and how to upload it.