Dynamic Host DNS Registration

[Auer, Karl James]

> > >> Don't allow your Windows systems to update the DNS zone,=20
> > >> have the DHCP server do that.
> > > I don't think my SMC router/DHCP-server can do that. =20

Maybe the little DHCP servers built into consumer electronics don't do
that, but any serious DHCP server can do it.  Including the most popular
open source server, ISC DHCP. Since you need a fully fledged DNS server
to handle the updates, and a DNS server is by definition on a fixed IP
address, you might as well run a DHCP server on the same box and let
your local machines get their addresses from that instead of from the
router. You get a lot more control, you get DDNS, and you get
independence from the router.

> The DHCP specification discusses the communication between the DHCP=20
> client and server.  I don't think it says anything about DHCP servers=20
> updating DNS servers.  That's something many DHCP servers do,=20
> but it's an add-on for integration, not part of the DHCP protocol.

There are separate standards (still developing, I believe) covering
exactly *how* to update DNS entries dynamically, don't have the numbers
to hand. Exactly *what* gets updated and *when* is left up to the
DHCP-server. Most will insert an A record for the name and a PTR record
for the address, in the appropriate forward and reverse zones, when they
allocate an address. Different servers have different ways of working
out what zones to update. Most will remove the appropriate entries when
a lease expires. Most will mark their own entries (for example with an
encoded TXT record) and refuse to delete or overwrite entries they did
not create. All sensible stuff.

Regards, K.

--=20
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Karl Auer (karl.auer at id.ethz.ch)       Geschaeft/work +41- 1-6327531
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