Creating a nameserver pointing to another nameserver... is it slower?

Question

I'm creating a project on Microsoft Azure. We only get a nameserver instead of an IP address. Since I have multiple domains pointing to Azure, I would like to redirect all my domains to a nameserver that is redirecting to Azure. This way, if Azure change my nameserver, I’ll only have to change one nameserver instead of changing it for all my domains.

However, is it a bad practice to create a nameserver pointing to another nameserver. Is it slower to resolve the IP address ?

Thank you !

Answer 1

I guess you mean having NS records point to a CNAME record?

It's not allowed. However, it usually works. Doing this has always been discouraged but the original DNS specification was never perfectly clear about it.

RFC 2181 clarifies that it is not allowed, and RFC 1912 is relevant too. This ServerFault question contains more details and is where I found the refences to those two RFCs.

Nonetheless, it "usually" works (but I wouldn't recommend doing it). In answer to your question, yes, it will be slightly slower (there's an extra name that must be resolved) but not significantly, and resolvers will cache everything after the first time anyway.