looking for reference to correct behavior

[Maria Iano]

By saying things like "We load the authoritative data into memory so  
that is also cached data" and other nonsense the vendor is stating  
that this behavior is in compliance with the RFCs and refusing to fix  
their code. Very frustrating, as I believe this behavior is clearly  
wrong and also seems to me to be a security issue.

Thanks for your help anyway!
Maria

On May 11, 2009, at 2:33 PM, Kevin Darcy wrote:

> The "resolver algorithm" in RFC 1034, Section 5.3.3, states
>
>   1. See if the answer is in local information, and if so return
>
>         it to the client.
>
>
> and is further detailed as
>
>   Step 1 searches the cache for the desired data. If the data is in  
> the
>   cache, it is assumed to be good enough for normal use. Some  
> resolvers
>   have an option at the user interface which will force the resolver  
> to
>   ignore the cached data and consult with an authoritative server.  
> This
>   is not recommended as the default. If the resolver has direct  
> access to
>   a name server's zones, it should check to see if the desired data is
>   present in authoritative form, and if so, use the authoritative  
> data in
>   preference to cached data.
>
> This would be a case where the resolver "has direct access to the  
> name server's zones", so there is no debate, in my opinion, that the  
> resolver in question is doing The Wrong Thing.
>
> RFC 2181 also makes it clear that authoritative data ranks higher  
> than cached data, so that could also be used as a relevant normative  
> reference.
>
> - Kevin
>
> Maria Iano wrote:
>> My apologies if this is considered to be too off-topic.
>>
>> I have a situation where my company uses a number of servers with a  
>> commercial DNS implementation (in addition to our BIND servers).  
>> The other implementation is Windows DNS, and there is some behavior  
>> that I do not think is acceptable, but which the vendor claims is  
>> acceptable behavior. I really want them to fix this bug (as I  
>> consider it), but first I need to get general agreement that it is  
>> a bug. I will be looking through the RFCs as much as I can time  
>> for, but haven't found what I need yet. Since my next meeting with  
>> the vendor is tomorrow, I thought I would also ask if anyone can  
>> already point me to a relevant RFC or other reference.
>>
>> Here is the behavior that I think is not acceptable.
>>
>> We have configured a zone on the windows server - dmz.example.com.  
>> This zone contains an A record for foo.dmz.example.com with IP  
>> address 10.240.240.240. The zone example.com is hosted elsewhere  
>> and contains a CNAME record foo.example.com pointing to  
>> foo.dmz.example.com.
>>
>> If the cache has just been cleared, and a client asks the WIndows  
>> DNS server for foo.example.com, it has a forwarding server to which  
>> it forwards the request. The forwarding server hands it back the  
>> CNAME record but it also hands back an A record for  
>> foo.dmz.example.com pointing to an incorrect IP address  
>> 192.168.240.240. The Windows DNS server accepts this A record for  
>> foo.dmz.example.com with an incorrect IP address into its cache,  
>> and hands out that incorrect information to the client. Even though  
>> it concurrently has dmz.gannett.com configured on it as a primary  
>> zone with a record for that same owner name pointing to a different  
>> IP address.
>>
>> I believe it shouldn't do that. Since it hosts dmz.example.com as a  
>> primary zone, I think it should discard that bad A record and hand  
>> back its own.
>>
>> The vendor's argument is that it should blindly trust the  
>> forwarding resolver.
>>
>> Can anyone point me to an RFC or reference about this?
>>
>> Thanks,
>> Maria