Meowy Catkin
Meow!
Almost but duns can and do have white markings. The gene is entirely separate from the dun gene. However for the breeds that dun is found in (esp Highlands) white markings are very frowned on.
Very true. Quarter horses have both the dun and cream gene in the breed (so you can have dunalinos and dunskins) and they can also have white markings, plus as far as I know, white markings aren't frowned upon in that breed.