Re: Spain was offline

["Crist Clark" <Crist.Clark () globalstar com>]

> > > On 8/31/2006 at 8:22 AM, <Michael.Dillon () btradianz com> wrote:
[snip]

> An ISP could run a modified DNS relay that replicates all
> responses to a special cache server which does not time out
> the responses and which is only used to answer queries when
> specified domains are unreachable on the Internet.
>
> For instance, if you specified that all .es responses were
> to be replicated to the cache and that your DNS relay should
> divert queries to the cache when .es nameservers are *ALL* 
> unreachable, then the impact of this type of outage is greatly
> reduced. You could specify important TLDs to be cached this way
> as well as important domains like google.com and yahoo.com.
> The actual data cached would only be data that *YOUR* customers
> are querying anyway. In fact, you could specify that any domain
> which receives greater than x number of queries per day should
> be cached in this way.

> From what I've inferred from some other comments about the
failure, it seems that the DNS servers were not unreachable
or otherwise unavailable, but rather that the .es zone data
was corrupted.

Such a failure wouldn't trip the backup system you describe.
How does an automated system tell the difference between
a "real" NXDOMAIN and a erroneous one? It would take human
intervention to turn it on in many potential failure modes.
How much of a window is there where the ISP can positively
identify a failure and start up their backup before the TLD,
or whatever external DNS entity, gets its own act together?
-- 

Crist J. Clark                               crist.clark () globalstar com
Globalstar Communications                                (408) 933-4387


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