[dns-operations] Name server turning off RD bit in response - just curious

[Roy Arends]

There is a little bit more off:

1) All classes are converted to 'IN', try dig with CLASS12345 (or any class other than 1) and you'll get
;; Question section mismatch: got name-services.com/A/IN

2) single label qnames often get expanded weirdly

dig @dns5.name-services.com com

; <<>> DiG <<>> @dns5.name-services.com com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62972
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 5

;; QUESTION SECTION:
;com.				IN	A

;; ANSWER SECTION:
:\005com.\005com.	3600	IN	A	69.64.147.243

(first character looks random)

No doubt there is more unexpected random behaviour. 

Roy

On Aug 7, 2012, at 1:40 PM, "Faasen, Craig" <craig.faasen at roche.com> wrote:

> Hello,
> 
> I noticed that the "rd" flag was missing from the output of a standard (recursive) dig against some (*) of the name-services.com name servers:
> $ dig @dns5.name-services.com. name-services.com. | grep flags
> ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 5
> 
> (*) dns1 and dns5 show this behavior, dns2-4 are "normal".
> 
> Using dig.pl (Net::DNS::Toolkit):
> $ dig.pl -h @dns5.name-services.com. name-services.com.
> 
>  ID      => 4439
>  QR      => 0
>  OPCODE  => QUERY
>  AA      => 0
>  TC      => 0
>  RD      => 1
>  RA      => 0
>  Z       => 0
>  AD      => 0
>  CD      => 0
>  RCODE   => NOERROR
>  QDCOUNT => 1
>  ANCOUNT => 0
>  NSCOUNT => 0
>  ARCOUNT => 0
> 
>  ID      => 4439
>  QR      => 1
>  OPCODE  => QUERY
>  AA      => 1
>  TC      => 0
>  RD      => 0
>  RA      => 0
>  Z       => 0
>  AD      => 0
>  CD      => 0
>  RCODE   => NOERROR
>  QDCOUNT => 1
>  ANCOUNT => 1
>  NSCOUNT => 5
>  ARCOUNT => 5
> 
> ; <<>> dig.pl 1.11 <<>> -h @dns5.name-services.com. name-services.com.
> ;;
> ;; Got answer.
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4439
> ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 5
> 
> <snip>
> 
> RD is set to 1 in the query, but is 0 in the response.
> Which is not compliant with RFC 1035: "RD Recursion Desired - this bit may be set in a query and is copied into the response."
> 
> Out of curiosity, any idea why a name server would want to change the RD bit ? (except to break an unsuspecting script ;)
> 
> Thanks and regards,
> -- craig
> 
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