[jdev] How to handle SRV lookups when the root domain is referenced

[Bruce Campbell]

On Tue, 2 May 2006, Dave Cridland wrote:

> On Sun Apr 30 14:16:57 2006, Bruce Campbell wrote:
>> Both of these documents also refer to DNS-SRV (rfc2781), which states that 
>> if the target of the sole (successful) SRV answer is the root domain ('.'), 
>> then 'abort'.
> You mean RFC2782, which states that 'A Target of "." means that the service 
> is decidedly not available at the domain.' - later, in the description of how 
> to use SRV records, it merely says 'abort'.
>
> This means your interpretation must be correct - sort of. The server could 
> lookup records in _simple.example.com, for instance, if it were capable of 
> gatewaying to SIMPLE, but no server to server XMPP service is available.

Something that struck me over the course of today, is that although a 
(sole) target of '.' means 'not available', and imho, 'stop completely', 
it could be argued that since XMPP-IM encourages SRV lookup chains, it 
might be permissible to continue with looking up 
_im._xmpp.example.com/_pres._xmpp.example.com , depending on whether you 
view generic server-to-server XMPP as being different from 
message-or-presence-server-to-server XMPP.

> Definitely it's wrong to resolve example.com and try randomly connecting to 
> it - not only wrong, but arguably illegal, since you've been explicitly told 
> there is no such service at the domain.

Agreed, but enforcement is another matter.

-- 
   Bruce Campbell