[hashworks]

If you host a hidden primary yourself you get that easily.

[Sesse__]

Many DNS providers also don't support having an external primary.

[alanpearce]

Hurricane Electric support a hidden primary as part of their free DNS nameserver service (do you actually want to expose your primary when someone else can handle the traffic?)

https://dns.he.net

[nulbyte]

Do most of them let you add an NS record?

[rfmoz]

Give a try to DNSMadeEasy or RcodeZero