The best practice for me over the time is to have one additional DNS server. With the prices so low for linux virtuals you can simply pick provider, setup any Linux (I prefer debian and bind combination) and create secondary DNS server. It should cost you really minimum but you will keep your NS servers alive all the time.
Once frustrated with the Cloudns.net service I have decided to use Anycast Premium DNS from Godaddy. But it was such awful experience that just after two days I have asked for refund. Few points I dont like about Premium DNS:
- Only two Nameservers - this might be enough but I live by saying more is better
- Vanity servers - this is really showstopper for me. You can use vanity servers only for domains hosted by GoDaddy.com. What is the point? Cloudns.net is not asking about domains and their registration. You have it, you setup Cloudns.net nameservers (or vanity nameservers) and that's it.
- Unbelievably slow and difficult to use control panel - Where was the UX designer when they developed Godaddy.com control panel? It is really difficult to use. And I have been using them for over 4 years for domains. Showing control panel to my wife I realized she couldnt move there and find anything I asked for. Fail.
Overall, I like Cloudns.net and they have added new servers and promised to make sure they will completely stop service failures. We shall see, I have my own backup DNS server so I can sleep much better now.