[AusNOG] [v6z] Re: Google DNS 8.8.8.8

[Scott Howard]

On Sat, Apr 23, 2011 at 11:12 AM, Andrew Cox <andrew at accessplus.com.au>wrote:

> Still makes it a pain if you're using multiple providers for a network
> (office or home network with dual adsl feeds or 3G backups etc).
>

If you've to the point where you're running redundant links, you've probably
also to the point where you can run your own nameserver - either fully
recursive, or with forward entries to your two upstreams.


Can anyone shed any light on why there isn't more interest in anycast DNS
> servers across ISP networks?
>

Given that anycast is extensively used for DNS servers (8.8.8.8 IS anycast,
as are 4.2.2.1-6, and countless other ISP DNS servers), I'm presuming that
you're referring to the concept of a single IP address(es) that all ISPs
would run their own DNS servers on, so you would always end up going to your
ISPs DNS servers regardless of which ISP you were on?

Whilst this might be a good idea in theory, realistically it's going to have
the same issues that 6to4 has (which uses an anycast address of 192.88.99.x)
in that unless you can get every ISP on the planet to support it, you're
going to end up with poor performance to from some ISPs, and complete
failures from others (either the network isn't advertised at all, or it is
and ends up on a DNS server that then rejects the query).

  Scott.
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