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Date: Tue, 10 Jan 2023 11:28:45 -0500
From: Rich Felker <dalias@libc.org>
To: "zhoujingqiang (A)" <zhoujingqiang1@huawei.com>
Cc: "musl@lists.openwall.com" <musl@lists.openwall.com>,
	liudongxu <liudongxu3@huawei.com>,
	"Yulu(Brooklyn,RTOS)" <yulu20@huawei.com>,
	Nixiaoming <nixiaoming@huawei.com>, Wangxu <wangxu72@huawei.com>,
	qiuguorui <qiuguorui1@huawei.com>,
	"wangyunhe (A)" <wangyunhe@huawei.com>
Message-ID: <20230110162844.GE4163@brightrain.aerifal.cx>
References: <c11794d249654abd8f81cdeef6bc0330@huawei.com>
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In-Reply-To: <c11794d249654abd8f81cdeef6bc0330@huawei.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Subject: Re: [musl] MAXNS should be increased

On Tue, Jan 10, 2023 at 12:57:34AM +0000, zhoujingqiang (A) wrote:
> Hello,
> 
> Currently, MAXNS is set to 3 which limits the number of nameserver.
> It is not enough to meet most people's requirements for private DNS
> servers. In my scenario, my client needs to access the networks of
> six companies. Each company provides active/standby servers to
> obtain private domain names. Three DNS servers are far from enough.
> 
> Expect to increase MAXNS to 12
> 
> Glibc has similar open bug[1]. The concern is that changing MAXNS
> would cause an ABI break. Musl does not have this problem since
> __res_state is stub.
> [1]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=998211
> 
> I am not subscribed and want to be Cc'd on replies, thanks.

Multiple nameservers in resolv.conf are not a means to do unioning of
conflicting DNS namespaces. They're expected to be purely redundant
with non-conflicting (i.e. if one doesn't know about something another
does, it has to ignore the query or ServFail, not NxDomain or NODATA
it) records. If you need unioning of distinct spaces using custom
rules for resolving conflicts, you need a special nameserver running
on localhost or somewhere else you control that performs this logic.

Rich