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DNS
2013 7 19DNS Summer Days 2013
JPRS
@OrangeMorishita
DNS
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: 1965 9 21 47 :
7
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1
DNS
RFC 2181
DNS Summer Days 2012
DNS
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2
RFC 1034/1035
DNS Summer Days 2012
DNS
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DNS
1.2. referral3. DNS4.
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DNS
DNS
dig DNS
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dig
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1.
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jpexample.jp
jp kr com org net
example.jp example2.jp example3.jp
www
DNS
DNS Summer Days 2012
DNS
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dig DNS +norec dig BIND 9.9.0 +noedns
additional section EDNS0 OPT
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.jp.
;; ADDITIONAL SECTION:ns1.example.jp. 86400 IN A 192.0.2.1
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answer section flags aa answer section answer section 0
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.jp.
;; ADDITIONAL SECTION:ns1.example.jp. 86400 IN A 192.0.2.1
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authority section NS additional section NS
IP A/AAAA
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.jp.
;; ADDITIONAL SECTION:ns1.example.jp. 86400 IN A 192.0.2.1
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A/AAAA
additional section
NS A/AAAA authority section
NS
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$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.net.
;; ADDITIONAL SECTION:ns1.example.net. 86400 IN A 192.0.2.1
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NS
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.net.
;; ADDITIONAL SECTION:ns1.example.net. 86400 IN A 192.0.2.1
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ns1.example.net 192.0.2.1a.dns.jp
alternic.net
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.net.
;; ADDITIONAL SECTION:ns1.example.net. 86400 IN A 192.0.2.1
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flags aa
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.jp.
;; ADDITIONAL SECTION:ns1.example.jp. 86400 IN A 192.0.2.1
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NSin-
bailiwick name
$ORIGIN jp.@ 86400 IN SOA example.jp. 86400 IN NS
ns1.example.jp.
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1
$ORIGIN jp.@ 86400 IN SOA example.co.jp. 86400 IN NS
ns1.example.ne.jp.
$ORIGIN jp.@ 86400 IN SOA example.jp. 86400 IN NS
ns1.example.ne.jp.
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2
$ORIGIN .@ 86400 IN SOA jp. 86400 IN NS a.dns.jp.
$ORIGIN .@ 86400 IN SOA com. 86400 IN NS a.gtld servers.net.
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$ORIGIN jp.@ 86400 IN SOA
1 example.jp. 86400 IN NS ns1.example.jp.2 example.jp. 86400 IN
NS a.ns1.example.jp.3 example2.jp. 86400 IN NS ns1.example.com.4
example3.jp. 86400 IN NS ns1.example.jp.5 example.co.jp. 86400 IN
NS ns1.example.co.jp.6 example.ne.jp. 86400 IN NS
ns1.example.ad.jp.7 example4.jp. 86400 IN NS ns1.example.or.jp.
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$ORIGIN jp.@ 86400 IN SOA
1 example.jp. 86400 IN NS ns1.example.jp.2 example.jp. 86400 IN
NS a.ns1.example.jp.3 example2.jp. 86400 IN NS ns1.example.com.4
example3.jp. 86400 IN NS ns1.example.jp.5 example.co.jp. 86400 IN
NS ns1.example.co.jp.6 example.ne.jp. 86400 IN NS
ns1.example.ad.jp.7 example4.jp. 86400 IN NS ns1.example.or.jp.
1 23 4
56 7
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NSNS
DNS
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NSNS DNS
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DNS BIND 9 NSD
DNS
A/AAAA
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www.iij.ad.jp www.iij-ii.co.jp www.iij4u.or.jp A JP DNS
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$ dig +norec +noedns www.iij.ad.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 4
;; QUESTION SECTION:;www.iij.ad.jp. IN A
;; AUTHORITY SECTION:iij.ad.jp. 86400 IN NS
dns0.iij.ad.jp.iij.ad.jp. 86400 IN NS dns1.iij.ad.jp.
;; ADDITIONAL SECTION:dns0.iij.ad.jp. 86400 IN A
210.138.174.16dns0.iij.ad.jp. 86400 IN AAAA
2001:240:bb41:8002::1:16dns1.iij.ad.jp. 86400 IN A
210.138.175.5dns1.iij.ad.jp. 86400 IN AAAA
2001:240:bb4c:8000::1:5
www.iij.ad.jp
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www.iij-ii.co.jp$ dig +norec +noedns www.iij ii.co.jp a
@a.dns.jp;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 2,
ADDITIONAL: 0
;; QUESTION SECTION:;www.iij ii.co.jp. IN A
;; AUTHORITY SECTION:iij ii.co.jp. 86400 IN NS dns
b.iij.ad.jp.iij ii.co.jp. 86400 IN NS dns c.iij.ad.jp.
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www.iij4u.or.jp iij.ad.jp
$ dig +norec +noedns www.iij4u.or.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 4
;; QUESTION SECTION:;www.iij4u.or.jp. IN A
;; AUTHORITY SECTION:iij4u.or.jp. 86400 IN NS
dns0.iij.ad.jp.iij4u.or.jp. 86400 IN NS dns1.iij.ad.jp.
;; ADDITIONAL SECTION:dns0.iij.ad.jp. 86400 IN A
210.138.174.16dns0.iij.ad.jp. 86400 IN AAAA
2001:240:bb41:8002::1:16dns1.iij.ad.jp. 86400 IN A
210.138.175.5dns1.iij.ad.jp. 86400 IN AAAA
2001:240:bb4c:8000::1:5
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DNS
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DNSNS
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1/2
additional section NSA/AAAA
authority section
NS
pseudo-glue
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2/2
NS
DNS DNS
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2. referral
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referral
referral
referral DNS referral example.jp ns1.example.jp
$ dig +norec +noedns www.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.jp.
;; ADDITIONAL SECTION:ns1.example.jp. 86400 IN A 192.0.2.1
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DNS
JP DNS ns1.example.com
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DNS-OARC 2009Upward Referrals Considered Harmful
NANOG 45Upward Referrals Considered Harmful Peter Losher
Upward referralsUpward Referrals Considered Harmful
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Upward referrals
BIND 9recursion no;
referral BIND 8
Upward referrals$ dig +norec +noedns www.example.jp a @ DNS;;
flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 0
;; AUTHORITY SECTION:. 518400 IN NS a.root servers.net.. 518400
IN NS b.root servers.net.
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Upward referrals
referral
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RFC 1034
4.3.1. Queries and responsesThe way that the name server answers
the query depends upon whether itis operating in recursive mode or
not:
The simplest mode for the server is non recursive, since itcan
answer queries using only local information: the responsecontains
an error, the answer, or a referral to some otherserver closer to
the answer.
referral
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Upward referrals DNS
DNS . IN NS 47 Upward referrals 256
ISPrime
Upward Referrals Considered Harmful
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Upward referrals
BIND 9 additional from cache no;allow query cache { none; };
BIND 9
named.root
REFUSED$ dig +norec +noedns www.example.jp a @ DNS;;
>>HEADER
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Upward referrals
NSD
SERVFAIL PowerDNS
send-root-referral=no yes BIND 8 lean BIND 9
djbdns
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DNS BIND 9
NOTIFY BIND 9
NOTIFY
IPBIND 9
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BIND 9 named.confNOTIFY
DNS BIND 9DNS
DNS
NS RRSetSOA MNAME NS
NOTIFY
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BIND 9NOTIFY
allow transfer named.conf IP
DNS
DNS
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BIND 9NOTIFY
zone "example.jp {....// also notify explicit IP NOTIFYnotify
explicit;// NOTIFY IPalso notify { 192.0.2.53; 198.51.100.53;
};
};
zone "example.jp {....// NOTIFY NOTIFY// notify no; NOTIFYnotify
no;
};
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3.DNS
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RFC RFC 2181
Clarifications to the DNS Specification DNS
5.4.1. Ranking data source
trustworthiness
AA answer authority additional
CNAME
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RFC 2181 5.4.1. Ranking data
answer section
authority section
answer sectionanswer section
additional informationauthority sectionadditional
information
most
leastadditional section additional information
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the least
NS authority section
A/AAAA additional information
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BIND 9 NSD
BIND 8answer section
$ dig +norec +noedns ns1.example.jp a @a.dns.jp;; flags: qr;
QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1;; AUTHORITY
SECTION:example.jp. 86400 IN NS ns1.example.jp.
;; ADDITIONAL SECTION:ns1.example.jp. 86400 IN A 192.0.2.1
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DNS DNSNS
answer section
increase
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DNS
NS/ NS/A NS/
NA/A NS/
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NSNS
DNS
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NS/ NS/A NS/A NS/
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4.
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2008
*1 1 2
DNS 3
*1 BIND (Kaminsky Bug )
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1
Web
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL:
1
;; QUESTION SECTION:;(random).example.jp. IN A
;; ANSWER SECTION:(random).example.jp. 86400 IN A ( IP )
;; AUTHORITY SECTION:(random).example.jp. 86400 IN NS
www.example.jp.
;; ADDITIONAL SECTION:www.example.jp. 86400 IN A 192.0.2.234(
)
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2
Web
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL:
1
;; QUESTION SECTION:;(random).example.jp. IN A
;; ANSWER SECTION:(random).example.jp. 86400 IN A ( IP )
;; AUTHORITY SECTION:example.jp. 86400 IN NS www.example.jp.
;; ADDITIONAL SECTION:www.example.jp. 86400 IN A 192.0.2.234(
)
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3
DNS p.298
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL:
1
;; QUESTION SECTION:;(random).www.example.jp. IN A
;; ANSWER SECTION:(random).www.example.jp. 86400 IN A ( IP )
;; AUTHORITY SECTION:www.example.jp. 86400 IN NS
www.example.jp.
;; ADDITIONAL SECTION:www.example.jp. 86400 IN A 192.0.2.234(
)
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1 2 authority section
1: (random).example.jp NS 2: example.jp NS
1 2 3 /answer section
1/2: (random).example.jp A 3: (random).www.example.jp A
authority section 1/2: 3: www.example.jp NS
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12 additional information
BIND 9
2786. [bug] Additional could be promoted to answer. [RT
#20663][bug] Additional answer
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3 authority section additional information
www.example.jp
answer section
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authority section additional information
answer section
DNS
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192.0.2.234DNS
DNSDNS
answer section
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5.4.1. Ranking data
answer section
authority section
answer sectionanswer section
additional informationauthority sectionadditional
information
most
least
3
1/2
3
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RFC 2181
RFC 2181
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Q&A
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