[dns-wg] Fwd: [enum-wg] Tier-2 provisioning: NS vs CNAME/DNAME

On 15 Jul 2004, at 11:07, Jim Reid wrote:

> You lose the granularity of control and the flexibility to let
> customers manage their delegations. I'm presuming you plan to have all
> your numbers CNAME'd into a single zone file rather than discrete zone
> files for each zone.

I see it quite the other way around: you _gain_ flexibility.

The customer has a single point of administration for announcing the
delegation and changes thereto.  Once the CNAME has aged out from
resolver caches, there is no trace left of obsolete data in the 'golden
tree'.  If the T2 provider which the customer has just deserted delays
(or neglects) removing the relevant RRsets, so what ?  With NS, on
the other hand, you have to make sure that all the obsolete data on 
still
authoritative servers is eliminated.

> This might also get you into trouble with the
> competition authorities because the people using these CNAME'd numbers
> are locked in to your way of doing things.

Are you saying that the opportunity for restrictive practices is 
significantly
different according to which method you choose for implementing 
delegation ?

I really don't see this.

> For something like a DDI
> block for an organisation, this shouldn't be an issue. But if it was
> for all numbers in the Dublin area code (say), there would be a
> problem.

How is this different between the NS and CNAME implementations ?

> Registrants won't have the freedom to choose and switch DNS
> providers. Or decouple DNS hosting from the ISP/registrar they use to
> get their ENUM delegation.

See above.

Best regards,

Niall O'Reilly
UCD Computing Services