W2K multi-master features

[Kevin Darcy]

lderuaz at free.fr wrote:

> Hello,
>
> Our company is wondering wether or not use Microsoft DNS (a W2K/AD
> architecture is going to be implemented soon).
>
> Does W2K multi-master capacity really avoid the 'single point of
> failure caused if the primary dns server fails' (and so prevent any
> dynamic update) in a primary/secondary dns architecture ?
> IS there any characteristic offering absolute advantages for using
> Microsoft DNS ?
> We are currently using Bind and Lucent (VitalQIP) DNS servers.

BIND is a reference implementation of DNS, and since there is no
standardized way to do multi-master DNS replication, BIND itself does
not implement multi-master replication. However, product built on BIND
(possibly even QIP) might have a way to do multi-master replication. You
should check with them.

Failing that, the "sdb" mechanism in BIND 9 means that you could use a
variety of database backends. Maybe some of those support multi-master
replication within themselves.

Be aware however, that multi-master changes the basic nature of
DNS replication, and not necessarily all in a good way. How do you deal
with replication conflicts, for instance? Do you need increase
replication frequency because client apps that write data to one
quote-unquote "master" may freak out if the data is missing from another
quote-unquote "master" (think moving a laptop from one LAN to
another)? And, if so, what impact is that extra replication going to
have on your machine and network resources?

If you really need this level of redundancy, you might want to look
instead at a failover approach, where a slave can be quickly
reconfigured as a master if the real master fails. Now that BIND 9
supports update forwarding, this is a lot more feasible than it used to
be (theoretically at least: I admit I haven't tried it myself).


- Kevin