[enum-wg] Help with enum docs

On 1 Apr 2011, at 11:10, Peter Andreev wrote:

> Could someone provide me with examples of such collision and its  
> resolution?

The answer is already in the text you quoted.

There may be several NAPTR records for some domain name. RFC3403 calls  
this a collision. An application will do a lookup for that name, get a  
bunch of NAPTRs back and then have to make a decision about which ones  
are of interest. This can entail a bit of crunching on the DNS  
response: regexp rewriting, chasing non-terminal NAPTRs, order and  
preference handling, etc. This might be painful in some cases. In  
others, it's just an irritant.

The DNS does not provide a way of saying "please only send me the  
mailto: NAPTRs for this name" or "send me all the D2U NAPTRs for this  
name, but no E2U (ENUM) ones". So if you want application-specific  
responses to NAPTR lookups, you need to organise the DNS data in that  
way and then give the applications a priori knowledge of how you've  
done that. eg Skype could be told to look for an E2U skype NAPTR for  
you at skype.peter.example.com instead of peter.example.com and you  
only put such a NAPTR at that node in the name space.