[dns-operations] 答复: Limit on Name Servers & their IPs for a sub-domain

Davey Song(宋林健) ljsong at biigroup.cn
Thu Jan 18 02:57:39 UTC 2018

Hi James,

I once asked the very question years ago. I have some experience and
understanding on that.

The limit of 13 is in people's mind for long time. A typical example is 13
root servers. Although limit of 13 has technically long gong, but it became
a inertia as a operation choice. Other number limit does not change the
situation if you still using UDP to transmit DNS message. 

You may have heard that Yeti DNS project(http://yeti-dns.org ) in which the
scaling issue is one of topic. To your question, I composed a post in Yeti
blog. Hope it will help.


Best regards,

> -----邮件原件-----
> 发件人: dns-operations [mailto:dns-operations-bounces at dns-oarc.net] 代表
> James Stevens
> 发送时间: 2018年1月11日 23:11
> 收件人: dns-operations
> 主题: [dns-operations] Limit on Name Servers & their IPs for a sub-domain
> I am aware of the "traditional" limit of 13 NS records for a sub-domain,
is it
> considered that this still applies?
> A live test I ran indicated that multiple IPv4/IPv6 records for the name
> server get (roughly) the name number of queries.
> But, I only tested a small number of address - is there some reason (e.g.
> size, code restrictions, etc) that might mean more addresses would not
> This suggests a theoretical unlimited servers for a sub-domain, so long as
> are represented as additional IP Addresses against the same name.
> Is there any practical / theoretical / recommend limit ?
> I have seen a lab test that used two Class-A addresses and showed that
> all IPs received queries, but it was using a very limited range of
> vendor equipment.
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