Re: [dnsop] DNS Anycast revisited (fwd)

["Paul G" <paul () rusko us>]

----- Original Message ----- 
From: "Dean Anderson" <dean () av8 com>
To: "Paul G" <paul () rusko us>
Cc: <nanog () merit edu>
Sent: Tuesday, May 03, 2005 8:35 PM
Subject: Re: [dnsop] DNS Anycast revisited (fwd)


> On Tue, 3 May 2005, Paul G wrote:
>
> > > There seems to be no possibility for anycast to be "completely
coherent",
> > > so ultradns' anycast couldn't be "completely coherent" either.  But
Vixie
> > > mentions it to respond to comments by others about Ultradns'
particularly
> > > pervasive use of anycast.
> >
> > it may not be possible to make every service *consistent*, but it is
> > perfectly possible to make it coherent (i'm talking about coherency of
> > copies of a shared resource).
>
> This seems to be a trivial interpretation of "coherent". It is assumed
> that the copies of DNS _zones_ are kept in sync regardless of whether the
> servers are to traditional replicas or to anycasted replicas. No one ever
> claimed that zone transfers between the copies would be affected by
> anycast.  The "in-sync"-ness of the zone data is competely orthogonal to
> anycast. Roots are updated via back channels on non-anycast addresses, and
> not with AXFR.

i'm terribly sorry, but i'm unable to extract any meaning at all from these
statements. when i parse them, they make no sense at all (not in terms of
being wrong, just not understandable). could you rephrase them?

coherency and consistency are well-defined terms in systems engineering. we
are talking about dns queries and hence coherency of zone data (the shared
resource). i fail to see how this is open to any interpretation at all.

i snipped the rest for obvious reasons.

-p