Dynamic IP

Tim Wilde twilde at dyndns.org
Tue Jul 20 01:18:45 UTC 1999


There are a number of different ways you could accomplish what you would
like to do with the dynamic DNS situation.  Your idea of the dynamic DNS
provider handling all requests is one solution, but it is a somewhat
complex solution which all providers do not support or provide.

A somewhat simpler solution, and one which should not incur any
fees/charges to you if you choose providers wisely, could go something
like this.  You can set up to have the DNS for your domain hosted by a
free hosting provider, such as Granite Canyon (soa.granitecanyon.com).
There are some downtime issues, but from what I hear they have been
reliable lately.  Once you have them hosting the DNS for your domain, you
can set up an account with a dynamic DNS provider; I run one, I have
provided a list of a number of them at the end of this e-mail.  Once you
have the account established, you can make a CNAME record (or records) for
whatever hosts within your domain you would like to point to your server,
something like:
	www.yourdomain.com.	IN	CNAME	yourhost.dyndns.org.

For nslint to be happy with you at Granite Canyon, you will also have to
add " ; EXTREF GLOBALOK" to the end of that line (a comment to make the
syntax checker happy).  You could also make a wildcard (*) CNAME, not
always a good idea, but possible, like:
	*.yourdomain.com.	IN	CNAME	yourhost.dyndns.org.

Making sure you have that same comment as before to make the syntax
checker happy.  I know of a few people who have used this or a similar
tactic to dynamically alias hosts within their domain.

I hope this was helpful.  Here is a list of some Dynamic DNS providers:

www.dyndns.com		-- Fees for services, does dynamic domains
www.dyndns.org		-- Free dynamic DNS, not many extra features (yet)
www.dyns.cx		-- Free dynamic DNS
www.detour.net		-- Free basic services, charges for additions
www.oth.net/dyndns.html	-- A list of other services

Tim Wilde

---
Tim Wilde, Systems Administrator
Dynamic DNS Network Services
E-Mail: twilde at dyndns.org

On Mon, 19 Jul 1999, ray wrote:

> I have ADSL hooked up to a Linux server I am running 24/7.    I have
> another machine I am paying to have sit at an ISP on which I have been
> running bind and serve a few modest web sites off of a single IP with
> virtual hosting.  I followed along the DNS-HOWTO and bind handles a
> grand total of 3 domains.
> 
> I would like to shut the second machine down as it cost me real money.
> The ADSL machine runs dhcpcd and appears to have a 24 hr lease on an IP
> in principle.  In practice I have not seen the IP changed in 3 weeks (as
> long as I have had the ADSL installed).
> 
> How can I use my ADSL machine as an http server for  a few modest
> websites?  I hear there are somekind of dynamic dns servers out there.
> Where are they??
> 
> I would think it would go like this.  At internic I set up my domain
> www.eflownet.com to use the dynamic dns service as the primary and
> secondary name servers.  Then I update the dynamic nameserver when my
> IP changes.
> 
> But....
> 
> What happens during propogation lag.  My IP changes and I update it with
> my dynamic dns service but the old IP is still cached out there.
> A potential browser could get a non-authoritative lookup to the old IP
> and go the wrong machine.  If the dynamic dns service uses some
> technique (TTL??) to force authoritative lookups the dynamic dns machine
> is going to get swamped.  Is this how it works??
> 
> How about...
> 
> Does it make sense if I run bind on my ADSL machine and the dynamic dns
> machine forwards (somehow) all dns lookups to my machine.  Then I could
> handle all nitty gritty on my machine when the IP changes and the
> dynamic dns service guy just keeps track of my latest IP and sends all
> request for my domain eflownet.com to my ADSL machine.  Is this possible
> to setup?
> 
> If someone could just point me to some of these dynamic dns service
> providers I read their FAQ's and HOW-TOs to see how this thing works.
> 
> Thanks in advance for your time.
> 
> 
> Regards,
> 
> Ray Racine
> 
> 
> 
> 



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