My DNS arrangements are comprised of registrars, my own nameservers, and Linode acting as a slave DNS for some of my domains. I'll try to outline it below.
Namecheap.com, domains.google.com, and domain.mn are my registrars.
I've added glue records at namecheap to point to ns1.box.jtcol.com, ns2.box.jtcol.com.
I may have added glue records pointed toward a VestaCP machine; I'll have to look into it.
I only have one domain here so far, just to try it out: 2b8n.com.
Cole.mn is registered via domain.mn
This is a Mail-in-a-Box that handles email for any of my domains that require it.
box also becomes the nameserver for whatever domains if provides email for.