Re: [dnsext] [Technical Errata Reported] RFC2782 (2984)

[Douglas Otis <[e-mail]>]

On 10/4/11 5:22 PM, Masataka Ohta wrote:
> Jordan Brown wrote:
>
>>>  From examples of the RFC:
>>>
>>> ; NO other services are supported
>>> *._tcp SRV 0 0 0 .
>>> *._udp SRV 0 0 0 .
>>>
>>> it is obvious that weight=0 means that the RR must not be
>>> selected.
>> Perhaps, but on the other hand it also says:
>>
>> Domain
>> administrators SHOULD use Weight 0 when there isn't any server
>> selection to do, to make the RR easier to read for humans (less
>> noisy). In the presence of records containing weights greater
>> than 0, records with weight 0 should have a very small chance of
>> being selected.
> Hmmmm, as the RFC says:
>
> 	Domain
>          administrators SHOULD use Weight 0 when there isn't any server
>          selection to do, to make the RR easier to read for humans (less
>          noisy).
>
>          A Target of "." means that the service is decidedly not
>          available at this domain.
>
> weight=0 in the examples I showed should not be significant, sorry.
>
> Then, I agree with you, except that
>
> 	- Selecting weight=0 entries in any order when all of
> 	the weight!=0 entries have been selected.
>
> should be:
>
> 	- Selecting weight=0 entries in random order when all
> 	of the weight!=0 entries have been selected.
Even use of "." as a null target is problematic when this convention is 
ignored.

What problem does a "." (null) service reference improve over simply not 
having an entry?  The use of wildcards for _label._label services seems 
rather limited.

-Doug