[plug] DNS zone transfers

[James Devenish]

In message <Pine.LNX.4.58.0412081439470.12161 at goldmund.pri>
on Wed, Dec 08, 2004 at 02:43:30PM +0800, Peter F Bradshaw wrote:
> If I delete the zone files on the slave it will update from the master.
> But it will not do so otherwise. What I want is for the slave to poll
> the master about once a day or so.

With slaves, you should be more interested in 'notifications' than
'polling'. This is because slaves should be receiving notifications from
your master whenever the zone is updated and reloaded. When this occurs,
they will compare serial numbers and perform any transfers that are
necessary. All servers that are listed in the zone's NS records should
be facilitated in this way. You may also have unlisted slaves, but they
will only receive notifications if your server is configured explicitly
for them. As Craig says, the solution is to a (a) maintain your SOA and
NS records properly (b) don't forget to prompt your master to reload the
revised zone information if you have modified it.

Note, of course, your workstations' usage and remote nameservers' usage
is largely dictated by the TTLs and timeouts in your zone's SOA record
(i.e. they do 'polling' and do not receive notifications). This means
that clients and remote networks suffer from the infamous 'propagation
delays'. Any primer on SOA records should explain the significance of
timeouts and TTLs.