[dnsop] DNS Anycast revisited (fwd)

Wed May 4 00:35:46 UTC 2005

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.

Though, the whole "complete coherency" statement seems to be nonsense, so
I can't really say that it wasn't what he meant. If it was, it had no
bearing on anything, certainly not on any concerns having to do with
Ultradns' operations.  The concern about Ultradns was the pervasive use of
anycast. As just pointed out, it seems they've altered this, perhaps as a
result of these concerns being aired. (You're welcome, but save the thanks
until we have a solid solution)

The following is interesting: *some* Vixie associates thought that asking
Nanog how many roots were anycast was considered off topic: (I think this
query also resulted from DNSOP discussions in Oct/Nov '04.)

(now, wasn't randy bush one of the people who was doing ad hominems on me
just now? So he knows I have a valid point, but took a shot anyway. Nice.  
Get 'em while you can, I guess)

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On Thu, Nov 11, 2004 at 06:03:42PM -0800, Randy Bush wrote:
>
> >> which roots are anycast?  c f i j k?
> > b m
>
> thanks.
>
> which are widely anycast, i.e. at more than three or four
> locations OR on three or more continents?
>
> randy

        and the good folks on nanog would know this why?

--bill
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