Re: [dnsext] zone cut semantics

[Brandon Black <[e-mail]>]

On Sun, Feb 20, 2011 at 2:44 PM, Jim Reid <[e-mail]> wrote:
> On 20 Feb 2011, at 20:14, Brandon Black wrote:
>
>> Isn't this really a matter of semantics?
>
> Yes: zone cut semantics, not language semantics.
>
>> The parent zone is
>> authoritative for everything beneath itself, even if it choses to use
>> that power of authority to give a delegation response.  e.g. the .com
>> servers are authoritative for www.example.com, but they choose to
>> delegate that answer to the NS for example.com.
>
> Nope. Query the .com name servers for the NS records for example.com. They
> correctly return a non-authoritative answer. It's only the name servers for
> example.com that are authoritative for example.com and will authoritatively
> answer that query. In other words, it's the child that's responsible for the
> zone's authoritative NS RRset, not the parent. Which is how things should be
> when you consider what delegation actually means: crossing an administrative
> boundary from one authority to another.
>
> Please think again about what you posted. The inference of what you say is
> that the root servers are authoritative for everything. That's clearly not
> true.

IMHO, this is where it's semantics.  The root servers are
authoritative for everything, that's why we believe their delegation
answers.  The AA-bit is just part of how the protocol signals
delegation of authority.  Yes, the child is responsible for its own NS
records while the parent delegates, but the parent can take away the
delegation at any time and serve the child's zone data directly.

This does come into play in the glue issues.  You can trust glue data
which falls within the delegating (parent) zone , but you can't
necessarily trust other glue records that might come in a response.
This is much like a corporate hierarchy model: the CEO is
authoritative for everything, but delegates decisions throughout a
hierarchy of lower level managers.  The fact that Joe the VP of Sales
is responsible for all Sales decisions doesn't take away the CEO's
authority over everything the company does.