I don't see dunskin. I see just bay dun. The first picture with the flash being used makes it look almost like dunskin, but the bottom two definitely don't. A buckskin dun would be creamier, but he is a "flatter" color.
Definitely not a dunskin that's a bay dun. Here is my dunskin they are much lighter and creamier because they have two dilution genes. As you can see there is a big color difference. He is a darker shade of dunskin even than most others I've seen. A lot of the dunskins I've seen in person are even lighter than this.
Agree there's definitely a dun gene there- the dorsal and the leg barring are dead giveaways for that. The lighting isn't the best in the photos but I don't really see a cream gene there. So I'm thinking bay dun.
Do you know the color of the parents? One of them would have to have a cream gene for this horse to have inherited one.