[dns-operations] To A or to AAAA - was Re: Signaling client

[Mark Andrews]

In message <20110120115805.GA3561 at xs.powerdns.com>, bert hubert writes:
> Some additional numbers, the top-25000 domains from Alexa, each queried
> twice, once AAAA for 'www.domain' and once for the bare domain:
> 
> Sending                                 Receiving                          
>   Queued                      50000       Received                    49990
>   Error -/-                       0       Timeouts                       10
>                                           Unexpected                      0
>  Sent                         50000      Total                        50000
> 
> DNS Status                                                                 
>   OK                            618                                        
>   Error                         426                                        
>   No Data                     48454                                        
>   NXDOMAIN                      492                                        
>   Unknowns                        0                                        
> Answers                       49990                                        
>   Timeouts                       10                                        
> Total                         50000                                        
> 
> The same for A:
> 
> Sending                                 Receiving                          
>   Queued                      50000       Received                    49999
>   Error -/-                       0       Timeouts                        1
>                                           Unexpected                      0
>  Sent                         50000      Total                        50000
> 
> DNS Status                                                                 
>   OK                          48173                                        
>   Error                         300                                        
>   No Data                      1041                                        
>   NXDOMAIN                      485                                        
>   Unknowns                        0                                        
> Answers                       49999                                        
>   Timeouts                        1                                        
> Total                         50000                                        
> 
> "Error" in this context means the PowerDNS Recursor answered with a
> SERVFAIL.  It does not imply anything about what the authoritative server
> said.
> 
> 	Bert

And if you look at the SERVFAILS for the non www names they almost
all come back to servers run by one company that puts the SOA record
in the answer section rather than the authority section.

; <<>> DiG 9.6.0-APPLE-P2 <<>> star8.net @f1g1ns2.dnspod.net aaaa +norec
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14030
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;star8.net.			IN	AAAA

;; ANSWER SECTION:
star8.net.		600	IN	SOA	f1g1ns1.dnspod.net. freednsadmin.dnspod.com. 1294639336 3600 180 1209600 180

;; Query time: 427 msec
;; SERVER: 221.204.215.58#53(221.204.215.58)
;; WHEN: Fri Jan 21 18:54:21 2011
;; MSG SIZE  rcvd: 104

The SERVFAILs for the www names are usually the result of returning
the parent zone's SOA record many of which are hosted by qq.com.

www.taotao.com.		86400	IN	NS	ns-cnc1.qq.com.
www.taotao.com.		86400	IN	NS	ns-cnc2.qq.com.
;; Received 143 bytes from 219.133.62.252#53(ns1.qq.com) in 3042 ms

taotao.com.		86400	IN	SOA	taotao.com. webmaster.taotao.com. 1186652624 300 600 86400 86400
;; Received 78 bytes from 60.28.1.157#53(ns-cnc2.qq.com) in 441 ms

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org