[dnsop] DNS Anycast revisited (fwd)

Wed May 4 14:19:28 UTC 2005

On 4 May 2005, at 09:52, Edward B. Dreger wrote:

>
> TF> Date: Wed, 4 May 2005 10:48:56 +0100
> TF> From: Tony Finch
>
> TF> Why would anyone use an anycast address as a client? Wouldn't it be
> TF> simpler to make all client connections from the machine's unicast 
> address?
>
> Maybe, maybe not.
>
> Take an anycast DNS provider that AXFR/IXFRs zones from its customers.
> Notifying them of all anycast addresses and keeping ACLs up-to-date
> isn't feasible.
>
> The obvious answer is to have a couple hosts pull zones from unicasted
> addresses.

Actually, the obvious answer is to use TSIG instead of address-based 
ACLs to authenticate zone transfers. But in cases where that's not 
possible (because the master servers don't want to implement it, and 
insist on address-based ACLs), there are hacks available. See

   http://www.isc.org/pubs/tn/isc-tn-2004-1.html#anchor14

for an example.

Joe