DNS zone validation warnings - do they matter?

Question

I have made a verification of a site of mine via intodns.com.

I have received the following warnings:

Different subnets - WARNING: Not all of your nameservers are in different subnets
Different autonomous systems- WARNING: Single point of failure
SOA MNAME entry - WARNING: SOA MNAME (mydomain.com) is not listed as a primary nameserver at your parent nameserver!

Does anyone know how to fix these? I see that many domains are having these issues. Apparently, they are working fine (including my site). I just want to know if I should be worried about this.

Thanks in advance, Gabriel

Answer 1

The first two warnings are all about best practise for resiliency.

Ideally you should operate your two name servers on completely different sites, and better yet have one of them on somebody else's network. Your DNS will work fine regardless, but if that one network goes down your names will stop resolving. Whether that's acceptable or not is up to you.

The last warning is about an apparent inconsistency in your SOA record.

Specifically, what they're saying is that if your parent zone NS records say something like:

example.com.  IN NS ns1.example.org.
              IN NS ns2.example.net.

then your SOA ought to list one of those two in the MNAME field. It's not a big deal, because the MNAME field is only used if you're doing dynamic DNS updates.

Answer 2

I must add that the DeNIC denies requests to set both nameservers onto the same subnet. I wonder why the InterNIC is allowing this. The problem behind this is that a subnet is handled by a router, and if that router goes down - so will your nameservers.

Best wishes, Fabian