Re: How to keep a static IP and let DNS addresses be dynamically updated on Linksys WRT54GS ?

On Wed, 24 Aug 2005 15:02:40 -0300, Derek Broughton
<news@xxxxxxxxxxxxxx> wrote:

>Not even with the sveasoft firmware? It's a pretty basic function of DHCP
>servers, I would have thought there'd be a way.

No. There is no feature or function of a DHCP server to prematurely
expire a lease. I would love to have this feature to force everyone
to renew their DHCP leases on command when I renumber a network.

You can try it yourself. Setup your router with a DHCP server using
whatever address you find useful such as 192.168.1.1. Connect with a
typical Windoze client which gets its IP address from the DHCP server
in the router. Now, dive into the routers DHCP server configuration
and change the /24 IP block to something like 192.168.111.1. This
should probably be done with a 2nd computah, but it will work using
just one machine. Now, do whatever you find entertaining on the
router to get the client to expire the lease prematurely and get a new
IP address in the correct /24 block. You can reboot, thrash,
broadcast, curse, or whatever, the stupid Windoze DHCP client will
just sit there on the wrong IP address until 50% of the lease time has
expired. It will then try to renew the lease and get a DHCPNAK which
will eventually convince it to ask for a new IP address. This is the
same as:
ipconfig /release
ipconfig /renew
My point is that the renewal has to be initiated by the client, not by
the DHCP server.

Methinks that PPPoE can force an update without also forcing a
disconnect. I know it can force a disconnect which automatically
requires that the PPPoE client get new IP/DNS/Gateway addresses. I
can see that on SBC dynamic DSL accounts where the IP address may
change several times a day for no obvious reason. However, I've also
noticed that the two DNS servers delivered never change.

>> 3. Call your ISP's support people and ask them *WHY* they are
>> juggling DNS servers. It might be that they have a flakey DNS server
>> and are doing repairs.

>I think he should do that in any case - DNS servers really shouldn't change
>that much. I can see a round-robin system where they want to balance load
>among a half-dozen or so servers, but _all_ (or at least most) of them
>should still be available.

Yeah. That's what I'm thinking. There's no obvious benefit to
juggling DNS server IP's. It will drive most client computahs nuts.
It would be nice to know what problem the OP is trying to solve.


--
Jeff Liebermann jeffl@xxxxxxxxxxxxxxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558
.

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