[Yeti DNS Discuss] 答复: 答复: [rfc-editor at rfc-editor.org: BCP 209, RFC 8109 on Initializing a DNS Resolver with Priming Queries]

Davey Song(宋林健) ljsong at biigroup.cn
Thu Mar 16 09:59:14 UTC 2017


Yes. They changed their strategy considering the transport protocol, good
for IPv6 resolvers.

Davey

-----邮件原件-----
发件人: 'Stephane Bortzmeyer' [mailto:bortzmeyer at nic.fr] 
发送时间: 2017年3月16日 17:33
收件人: Davey Song
抄送: discuss at lists.yeti-dns.org
主题: Re: 答复: [Yeti DNS Discuss] [rfc-editor at rfc-editor.org: BCP 209, RFC
8109 on Initializing a DNS Resolver with Priming Queries]

On Thu, Mar 16, 2017 at 05:23:36PM +0800,  Davey Song <ljsong at biigroup.cn>
wrote  a message of 46 lines which said:

> I notice that the it suggests that resolver needs to issue direct 
> queries for A and AAAA RRsets for names which does not fit in the size 
> of priming response. In that case, it will loosen the hard limitation 
> of 13 root.

Well, even with the very old 512B limit, you can still get some addresses:

% dig +nodnssec +noedns +bufsize=0 @f.root-servers.net NS .

; <<>> DiG 9.10.3-P4-Debian <<>> +nodnssec +noedns +bufsize=0
@f.root-servers.net NS .
; (2 servers found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 5038 ;; flags: qr aa rd;
QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 10 ;; WARNING: recursion
requested but not available

;; QUESTION SECTION:
;.			IN NS

;; ANSWER SECTION:
.			518400 IN NS k.root-servers.net.
.			518400 IN NS f.root-servers.net.
.			518400 IN NS h.root-servers.net.
.			518400 IN NS b.root-servers.net.
.			518400 IN NS j.root-servers.net.
.			518400 IN NS m.root-servers.net.
.			518400 IN NS g.root-servers.net.
.			518400 IN NS a.root-servers.net.
.			518400 IN NS l.root-servers.net.
.			518400 IN NS e.root-servers.net.
.			518400 IN NS c.root-servers.net.
.			518400 IN NS d.root-servers.net.
.			518400 IN NS i.root-servers.net.

;; ADDITIONAL SECTION:
a.root-servers.net.	3600000	IN AAAA	2001:503:ba3e::2:30
b.root-servers.net.	3600000	IN AAAA	2001:500:84::b
c.root-servers.net.	3600000	IN AAAA	2001:500:2::c
d.root-servers.net.	3600000	IN AAAA	2001:500:2d::d
e.root-servers.net.	3600000	IN AAAA	2001:500:a8::e
f.root-servers.net.	3600000	IN AAAA	2001:500:2f::f
g.root-servers.net.	3600000	IN AAAA	2001:500:12::d0d
h.root-servers.net.	3600000	IN AAAA	2001:500:1::53
i.root-servers.net.	3600000	IN AAAA	2001:7fe::53
j.root-servers.net.	3600000	IN AAAA	2001:503:c27::2:30

;; Query time: 9 msec
;; SERVER: 2001:500:2f::f#53(2001:500:2f::f) ;; WHEN: Thu Mar 16 10:30:21
CET 2017 ;; MSG SIZE  rcvd: 508

(The fact that they are all IPv6 is because the requests was done over IPv6.
If I use dig with -4, I get mostly IPv4 addresses. Note it is specific to
some root name servers. A, B and J prefer IPv4, even if the priming request
is done over IPv6.)





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