case in responses

Karl Auer kauer at biplane.com.au
Mon Aug 12 01:43:29 UTC 2013


Hi all.

I have an odd issue - a particular device is apparently ignoring
apparently legal DNS responses. The only differences I can see between
the responses that do work and the responses that don't work are that in
the responses that don't work: 

a) the case of the response has been folded to lower case

b) the response includes an additional servers section

Here are two samples. The first fails, and was obtained by querying a
MikroTik embedded caching server. The second works, and was obtained by
querying a BIND caching server. If we tell the device to query the
embedded server, it ignores the responses; if we tell the device to
query the BIND server, it works.

I guess I just want to know if the embedded server is doing anything
wrong in folding the case down, or if the other device is doing
something wrong by not accepting the folded response.

Regards, K.

kauer at karl:~/pcaps$ dig @192.168.1.1 pioneer.vTuner.com

; <<>> DiG 9.8.1-P1 <<>> @192.168.1.1 pioneer.vTuner.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16432
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 7, ADDITIONAL: 7

;; QUESTION SECTION:
;pioneer.vtuner.com.		IN	A

;; ANSWER SECTION:
pioneer.vtuner.com.	1800	IN	CNAME	primary8.vtuner.com.
primary8.vtuner.com.	1800	IN	A	173.193.193.67

;; AUTHORITY SECTION:
vtuner.com.		8745	IN	NS	ns1.securityspace.com.
vtuner.com.		8745	IN	NS	ns1.dnsmadeeasy.com.
vtuner.com.		8745	IN	NS	ns2.securityspace.com.
vtuner.com.		8745	IN	NS	ns0.dnsmadeeasy.com.
vtuner.com.		8745	IN	NS	ns4.dnsmadeeasy.com.
vtuner.com.		8745	IN	NS	ns2.dnsmadeeasy.com.
vtuner.com.		8745	IN	NS	ns3.dnsmadeeasy.com.

;; ADDITIONAL SECTION:
ns1.securityspace.com.	154	IN	A	67.19.79.219
ns1.dnsmadeeasy.com.	4002	IN	A	208.80.124.2
ns2.securityspace.com.	154	IN	A	66.36.230.78
ns0.dnsmadeeasy.com.	10840	IN	A	208.94.148.2
ns4.dnsmadeeasy.com.	692	IN	A	208.80.127.2
ns2.dnsmadeeasy.com.	10326	IN	A	208.80.126.2
ns3.dnsmadeeasy.com.	692	IN	A	208.80.125.2

;; Query time: 445 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Mon Aug 12 11:33:20 2013
;; MSG SIZE  rcvd: 339

The second works, and was obtained by querying a BIND caching server:

kauer at karl:~/pcaps$ dig @192.168.1.35 pioneer.vTuner.com

; <<>> DiG 9.8.1-P1 <<>> @192.168.1.35 pioneer.vTuner.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12903
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 7, ADDITIONAL: 0

;; QUESTION SECTION:
;pioneer.vTuner.com.		IN	A

;; ANSWER SECTION:
pioneer.vTuner.com.	1800	IN	CNAME	primary8.vTuner.com.
primary8.vTuner.com.	1800	IN	A	173.193.193.67

;; AUTHORITY SECTION:
vTuner.com.		83375	IN	NS	ns0.dnsmadeeasy.com.
vTuner.com.		83375	IN	NS	ns1.dnsmadeeasy.com.
vTuner.com.		83375	IN	NS	ns1.securityspace.com.
vTuner.com.		83375	IN	NS	ns2.dnsmadeeasy.com.
vTuner.com.		83375	IN	NS	ns2.securityspace.com.
vTuner.com.		83375	IN	NS	ns3.dnsmadeeasy.com.
vTuner.com.		83375	IN	NS	ns4.dnsmadeeasy.com.

;; Query time: 2477 msec
;; SERVER: 192.168.1.35#53(192.168.1.35)
;; WHEN: Mon Aug 12 11:36:02 2013
;; MSG SIZE  rcvd: 227


 
-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

GPG fingerprint: B862 FB15 FE96 4961 BC62 1A40 6239 1208 9865 5F9A
Old fingerprint: AE1D 4868 6420 AD9A A698 5251 1699 7B78 4EEE 6017



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