Very willing to share.
I had initially planned to use 2 different providers for name servers as redundancy. The domain I tested is still with the domain name registrar but the name servers are and have been for several years with Cloudflare. For my use case, that means that all DNS information is stored at Cloudflare. My domain name registrar also offers nameservers and a diverse range of DNS services.
I was not aware of what would happen if I continued to use Cloudflare’s name servers and added the registrars servers as well. Shortly after the DNS had propagated I noticed that my domain was no longer working. Cloudflare’s servers were no longer in use and only the registrars were working.
I went back to my registrars settings and removed their own servers, only leaving Cloudflare’s. Waited a little while for the DNS to propagate and everything was back to normal again.
I am sure that it’s possible to mix name servers for redundancy. After reading up some more, it would require a lot more work and my domain is nowhere near that certain type of use case for it either. Just thought it would be something interesting to try. Need to try stuff out in order to learn.
Finally, Cloudflare uses Anycast which more or less does the same thing. Several other providers out there that use Anycast as well.
If anyone else has something to share or comment on the matter, please do.