## page was renamed from DNS/1/security/cookies/返答
DNS/1/security/cookies/返答について、ここに記述してください。

5.  DNS Cookies Protocol Specification


5.1.  Originating a Request

5.2.  Responding to a Request

   If the server responds choosing (2) or (3) above,
   it SHALL generate
   its own COOKIE option containing both the Client Cookie copied from
   the request and a Server Cookie it has generated, and it will add
   this COOKIE option to the response's OPT record.

   Servers MUST, at
   least occasionally, respond to such requests to inform the client of
   the correct Server Cookie.  This is necessary so that such a client
   can bootstrap to the more secure state where requests and responses
   have recognized Server Cookies and Client Cookies.  A server is not
   expected to maintain per-client state to achieve this.  For example,
   it could respond to every Nth request across all clients.

-- ToshinoriMaeno <<DateTime(2017-04-06T09:23:13+0900)>>

== example ==
$ dig microsoft.com @ns1.msft.net
{{{
; <<>> DiG 9.11.0-P3 <<>> microsoft.com @ns1.msft.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: FORMERR, id: 35038
;; flags: qr aa rd; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1280
; COOKIE: 7cd9faea642d0270 (echoed)
;; QUESTION SECTION:
;microsoft.com.			IN	A

;; ANSWER SECTION:
microsoft.com.		3600	IN	A	23.100.122.175
microsoft.com.		3600	IN	A	23.96.52.53
microsoft.com.		3600	IN	A	191.239.213.197
microsoft.com.		3600	IN	A	104.40.211.35
microsoft.com.		3600	IN	A	104.43.195.251

;; Query time: 6 msec
;; SERVER: 208.84.0.53#53(208.84.0.53)
;; WHEN: Fri Apr 07 10:12:12 JST 2017
;; MSG SIZE  rcvd: 134
}}}