## page was renamed from DNS/CNAME返答 == NS/CNAME返答 == <> <> Answer SectionにCNAMEレコードがあるのに、RCODE 0 ではないことがある。 ここでは、CNAMEの指す先が存在する場合の返答を調べてみる。 　　CNAMEの指す先がnxdomainである場合もある。 [[/例]] == A record == {{{ %dnsq a www.ygc.jp ns1.dns.ne.jp ~/dnsq/wwwcn 1 www.ygc.jp: 101 bytes, 1+2+2+0 records, response, authoritative, noerror query: 1 www.ygc.jp answer: www.ygc.jp 3600 CNAME ygc.jp answer: ygc.jp 3600 A 49.212.207.32 authority: ygc.jp 3600 NS ns1.dns.ne.jp authority: ygc.jp 3600 NS ns2.dns.ne.jp }}} よくある設定で、よくある返答だ。 {{{ %dnsq txt www.ygc.jp ns1.dns.ne.jp ~/dnsq/wwwcn 16 www.ygc.jp: 107 bytes, 1+1+1+0 records, response, authoritative, noerror query: 16 www.ygc.jp answer: www.ygc.jp 3600 CNAME ygc.jp authority: ygc.jp 3600 SOA master.dns.ne.jp tech.sakura.ad.jp 2013052920 3600 900 3600000 3600 }}} この返答からTXTレコードの有無は判断できるか。(できそう w) 　　この返答はNoDataだと解釈してよいのだが、その理由はやや難解。 -- ToshinoriMaeno <> == TXT == {{{ %dnsq txt www.catal.jp 01.dnsv.jp ~/dnsq/wwwcn 16 www.catal.jp: 231 bytes, 1+2+4+0 records, response, authoritative, noerror query: 16 www.catal.jp answer: www.catal.jp 300 CNAME catal.jp answer: catal.jp 300 16 cv=spf1\040include:_spf.google.com\040include:bmsend.com\040include:spf.satorimail.net\040ip4:183.181.98.79\040~all authority: catal.jp 86400 NS 01.dnsv.jp authority: catal.jp 86400 NS 02.dnsv.jp authority: catal.jp 86400 NS 03.dnsv.jp authority: catal.jp 86400 NS 04.dnsv.jp }}} == AAAA == {{{ %dnsq aaaa www.ygc.jp ns1.dns.ne.jp ~/dnsq/wwwcn 28 www.ygc.jp: 42 bytes, 1+1+0+0 records, response, authoritative, noerror query: 28 www.ygc.jp answer: www.ygc.jp 3600 CNAME ygc.jp }}} {{{ %dnsq aaaa ygc.jp ns1.dns.ne.jp ~/dnsq/wwwcn 28 ygc.jp: 89 bytes, 1+0+1+0 records, response, authoritative, noerror query: 28 ygc.jp authority: ygc.jp 3600 SOA master.dns.ne.jp tech.sakura.ad.jp 2013052920 3600 900 3600000 3600 }}} aaaaがないことはこれで判明する。 こういう返事もする。 {{{ %dig -t aaaa www.ygc.jp @ns1.dns.ne.jp. ~/dnsq/wwwcn ; <<>> DiG 9.12.1 <<>> -t aaaa www.ygc.jp @ns1.dns.ne.jp. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22574 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;www.ygc.jp. IN AAAA ;; ANSWER SECTION: www.ygc.jp. 3600 IN CNAME ygc.jp. ;; AUTHORITY SECTION: ygc.jp. 3600 IN SOA master.dns.ne.jp. tech.sakura.ad.jp. 2013052920 3600 900 3600000 3600 ;; Query time: 11 msec ;; SERVER: 61.211.236.1#53(61.211.236.1) ;; WHEN: Thu Nov 29 11:01:15 JST 2018 }}} こっちの返事も。(dnsq, dig の違いではない。) {{{ %dig -t aaaa www.ygc.jp @ns2.dns.ne.jp. ~/dnsq/wwwcn ; <<>> DiG 9.12.1 <<>> -t aaaa www.ygc.jp @ns2.dns.ne.jp. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23634 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;www.ygc.jp. IN AAAA ;; ANSWER SECTION: www.ygc.jp. 3600 IN CNAME ygc.jp. ;; Query time: 8 msec ;; SERVER: 133.167.21.1#53(133.167.21.1) ;; WHEN: Thu Nov 29 11:02:55 JST 2018 ;; MSG SIZE rcvd: 53 }}} {{{ %dnsq aaaa www.catal.jp 01.dnsv.jp ~/dnsq/wwwcn 28 www.catal.jp: 44 bytes, 1+1+0+0 records, response, authoritative, noerror query: 28 www.catal.jp answer: www.catal.jp 300 CNAME catal.jp }}} この返事ではAAAAの有無は不明か。-- ToshinoriMaeno <> {{{ %dnsq aaaa www.accessplus.jp ns1.accessplus.jp ~/dnsq/wwwcn 28 www.accessplus.jp: 110 bytes, 1+1+1+0 records, response, authoritative, noerror query: 28 www.accessplus.jp answer: www.accessplus.jp 86400 CNAME accessplus.jp authority: accessplus.jp 10800 SOA ns1.accessplus.jp contact\056rep.gmail.com 1365529778 10800 3600 604800 10800 }}}