Dynamic zone transfers - performance

[John Horne]

On Mon, 2005-07-25 at 15:52 -0400, Kevin Darcy wrote:
> John Horne wrote:
> >
> >My question is whether anyone has experienced any problems when using
> >dynamic zones and a load of DHCP'ing PC's? In particular I guess I am
> >thinking about say a Monday morning when a lab of PC's is suddenly
> >turned on, they all DHCP and all dynamically update the DNS. I am
> >assuming that all these updates are sent to the secondary name servers
> >as incremental zone transfers, which is fine, but that there may well be
> >a lot of them all at once.
> >
> I know it's not really a *solution*, but you don't *have* to send 
> NOTIFYs to all of your slave servers all of the time. With BIND 9's 
> "notify explicit" feature, you can "turn off" NOTIFY for even a server 
> which is listed in the NS records of the zone. That would leave the 
> slave to wait for the tunable REFRESH interval to roll around before 
> checking the serial number. I've even heard about utilities that can be 
> used to manually send a NOTIFY to a particular server for a particular 
> zone, although I've never used one myself. Such a utility, in 
> conjunction with "notify explicit", could probably help you to 
> orchestrate an efficient use of your resources.
> 
Many thanks for the reply. The mechanism you mentioned of only
performing zone transfers at the refresh interval is a possibility.
Out-of-band methods will probably not go down too well with our remote
secondaries - if the DNS provides a zone transfer mechanism then I think
they would rather use that than having to configure something else to do
it.

We have decided to proceed with the MS servers performing dynamic
updates. Unfortunately I think that this is one of those scenarios which
is somewhat particular to each site. In our case the problem may be a
bunch of PC's all being turned on at the same time each morning -
probably not a problem for other non-educational sites. As such I think
we can only proceed by simply trying it and seeing what happens :-)

([OT] One problem: I mentioned to the MS DNS admin here that some of our
DNS records have particular TTL values. I was told that MS DNS does not
handle TTL values at all well but simply selects the lowest one in the
zone and then sets all the records to that! If that is true, and the
sort of thing that MS DNS does, then we may be taking a big step
backwards here!)



John.

-- 
---------------------------------------------------------------
John Horne, University of Plymouth, UK  Tel: +44 (0)1752 233914
E-mail: John.Horne at plymouth.ac.uk       Fax: +44 (0)1752 233839