Re: [musl] MAXNS should be increased

[Rich Felker <dalias@libc.org>]

On Wed, Jan 11, 2023 at 12:33:59PM +0000, zhoujingqiang (A) wrote:
> Thanks for reply,
> 
> It is not advisable to use localhost as a DNS server in embedded
> devices. It requires a resident process, which consumes many memory
> and bandwidth.

I hope you'll take the advice from others telling you why this isn't
the case, but regardless, the problem here is that you're asking for
something very different than what you actually want. You asked for a
higher MAXNS, but what you want is for the stub resolver to do
unioning for you. This is a much bigger request -- it's for policy
functionality that doesn't have existing precedent to be added to
libc. That's pretty much a hard no.

> We only provide devices, not servers. Servers are provided by
> carriers. We cannot write a build-in special servers on resolv.conf.
> 
> Our devices need to be sold to carriers around the world. There are
> many small carriers. They have their own domain names, which are
> non-conflicting but unique. In this case, increasing the MAXNS limit
> is the simplest and most efficient way.I think raising MAXNS won't
> hurt anything.

If any of them returns NxDomain for a query that a different one
returns an answer for, they *are* conflicting. Only if they return the
same answer or ServFail/timeout would they be non-conflicting. It's
possible to setup non-conflicting private zones this way (with
ServFail) but not common practice and I doubt it's what they've done.