dig -t txt output variation

[Mark Andrews]

In message <BLU156-W227D2D615494770D415A40F3540 at phx.gbl>, "M. Meadows" writes:
> We've noticed that the following command gets a variable result:
> 
> dig -t txt exacttarget.com @ns2.exacttarget.com +short
> 
> We get 2 results from this. Seems to be somewhat random. They are:
> 
> "v=3Dspf1 a mx ip4:207.250.79.101 ip4:207.67.98.192/27 ip4:72.18.216.98 inc=
> lude:cust-spf.exacttarget.com include:salesforce.com include:message1-spf-i=
> nc.exacttarget.com include:hotels-spf-inc.exacttarget.com ip4:206.246.157.1=
>  -all"
> "spf2.0/pra ip4:207.250.79.101 ip4:207.67.98.192/27 ip4:72.18.216.98 includ=
> e:cust-senderid.exacttarget.com include:salesforce.com include:message1-sen=
> derid-inc.exacttarget.com include:hotels-senderid-inc.exacttarget.com ip4:2=
> 06.246.157.1 -all"
> 
> 
> And=20
> 
> "spf2.0/pra ip4:207.250.79.101 ip4:207.67.98.192/27 ip4:72.18.216.98 includ=
> e:cust-senderid.exacttarget.com include:salesforce.com include:message1-sen=
> derid-inc.exacttarget.com include:hotels-senderid-inc.exacttarget.com ip4:2=
> 06.246.157.1 -all"
> "v=3Dspf1 a mx ip4:207.250.79.101 ip4:207.67.98.192/27 ip4:72.18.216.98 inc=
> lude:cust-spf.exacttarget.com include:salesforce.com include:message1-spf-i=
> nc.exacttarget.com include:hotels-spf-inc.exacttarget.com ip4:206.246.157.1=
>  -all"
> 
> 
> So ... the text output flips. Sometimes the spf1 entry is first ... sometim=
> es it's second.
> 
> We are aware of at least one application that sees the spf2.0 (if it's firs=
> t) and returns a neutral result for SPF testing. If the spf1 is first in th=
> e feedback it gets a pass for SPF.=20

The application is broken.
 
> ns2.exacttarget.com is running BIND 9.3.6-P1-RedHat-9.3.6-4.P1.el5_4.2.
> 
> Is this a BIND bug?=20

No.  The DNS does not preserve record order.  This is documented in RFC 1035.
 
> Thanks=2C
> Martin Meadows
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org