Glen R. J. Neff neff_glen at emc.com
Thu Oct 29 14:14:30 UTC 2009

Simon Hobson wrote:
> Banana Flex wrote:
>> but how can it work when the master goes down ? no DDNS works at this 
>> time ?
> Correct, DDNS stops working.
>> can the DHCP update the slave zone ? (stupid question sorry)
> No. And in general, you can't anyway (that's not a DHCP limitation, it's 
> a limitation of at least one of the major DNS implementations, and I 
> assume others). It is a definite possibility to create a database system 
> that allows updates to a slave when the master is down - but you've only 
> to look at the way failover works in DHCP to see how quickly the 
> complications build up when you take all the corner cases into 
> consideration. Not least of these complications is how to merge two sets 
> of updates - considering it's possible to have mutually incompatible 
> updates to apply.

ISC-bind can quite easily be configured to allow DDNS updates to "slave" 
servers for a zone.  You use the allow-update-forwarding{}; option in 
the zone declaration on the slave and specify the slave server IPs in 
with the allow-update{}; statement in the zone declaration on the master.


  * Glen R. J. Neff
  * RTP TSG Network Team
  * neff_glen at emc.com
  * EMC^2 == E^2

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