If I setup a second mail-in-a-box server (or another self hosted dns server, to sync zone fiels with etc…), exclusively for the dns server to help ease meltdown recoveries, would it be feeasable?
You might find that using a different, external DNS provider (e.g. Cloudflare, your registrar, etc) would be better if you’re finding you’re under a lot of DNS load.
I see… I was thinking to ease the setup in case everything crashes…
Anyway, Can I use these dns’s for my-self, like at home on my router for comcast etc…?
No, it’s not that kind of DNS server. The DNS server in Mail-in-a-Box is intended to answer queries about your domain only, not queries for every domain on the Internet.
Inside your home router, you’ll want to use your ISP’s DNS settings, or something like 22.214.171.124, 126.96.36.199, Quad9, etc.
Are you using the DNS server for purposes other than the email/basic-web that Mail in a Box provides?
Do keep in mind, if DNS is just for MiaB purposes; it is not so helpful to have a secondary as the primary DNS being down means something up with MiaB and even if folks could use secondary to get the IP of your MiAB they still may not be able to contact your box.
Take a look at Secondary DNS setup for some useful guidance.