Directional DNS

I searched the internet for this kind of feature to the site that offer DNS services but as of now I came up with few site having this kind of feature. Here are some of the site that have Directional DNS.

• http://dyn.com/
• http://www.ultradns.com/
• http://www.zerigo.com/
• http://www.dnsmadeeasy.com/

I don't know if there other sites beside on the list that offer this feature. if you have please feel free to comment it. Hope this will be helpful.