Topic: Simplifying the e-smith URL

[Lloyd Keen]

Is it possible to remove the e-smith from ftp.e-smith.mydomain.xxx and the like during the setup routine. I still haven't got my dynamic DNS figured out yet (BigPond Advance) so I'm assuming that this would be the URL that you would have to type to access the ftp or web server. And while were on the DNS subject, would someone be able to explain the basics of DNS using a dynamic IP. My understanding is this: You purchase a domain name from a registrar and their DNS servers handle any requests for your domain. They may or may not be able to redirect any requests for your domain to another site (so far so good??). In order for me to handle the dns on my domain would it be a simple matter of going to my registrar and changing the Primary DNS server for my domain to my dynamically assigned IP address???? Somehow I don't think that it would be this easy. If someone could offer some words of wisdom I would very much appreciate it.
Regards Lloyd

[Dan Brown]

"e-smith" isn't a necessary part of the hostname to access your machine from outside your LAN.  To access the machine from outside your LAN, you need either the IP address of the machine, or a hostname which resolves to that IP address.  That hostname can be anything.  The e-smith comes into play when you're using machines on your LAN.

DNS is pretty complicated, but here's generally how it works:

Every domain has at least two DNS servers, which tell the world whom to ask about that domain.  So, when you try to surf to www.yahoo.com, the 'net asks the DNS server for yahoo.com, which tells you that the IP is, for example, 204.71.200.75.  Your computer then connects to that IP address, and everything's fine.  When you register a domain, you tell the registrar who the DNS servers are for your domain.

So far, this sounds pretty simple.  However, there are two related concepts which complicate the issue.  The first issue is caching.  You see, my explanation above was oversimplified.  If everybody asked ns1.yahoo.com for yahoo.com's IP address, there'd be a lot of unnecessary network traffic, so local DNS servers (at your ISP, for example) cache the DNS records, keeping local copies for the length of time specified in those records.

So, let's recast the example.  You still want to go to www.yahoo.com, so your computer asks your ISP's DNS server who www.yahoo.com is.  That DNS server doesn't know, so it asks ns1.yahoo.com (yahoo's DNS server), gets the answer, gives it to you, and keeps it around for the rest of the day.  A few minutes later, your friend wants to go to www.yahoo.com, so his computer asks the ISP's DNS server.  This time, the DNS server knows the answer, so it gives it directly to your friend.

This leads to the second issue, which is propagation.  If yahoo.com changed its IP address between your visit and your friend's visit, your ISP won't know about it, because it caches the response for the whole day (actually, for about 11 hours in yahoo's case).  The length of time to cache a DNS record is specified in the record itself, but values of one day are pretty common.  Consequently, it often takes a day (or more) for changes to a DNS record to spread out to the rest of the 'net.

Now, this has been a brief overview of DNS in general.  How does dynamic DNS work?  Well, when you register your domain, you give the registrar the DNS servers of a dynamic DNS service.  The dynamic DNS service then gives you access to some automated way to update your DNS record, and publishes that DNS record.  But, unlike most DNS records, this one is published with a very short lifespan--about one minute.  So, your changes will propagate very quickly.

I hope this makes some sense, and helps explain what's going on.  If not, let me know, and I'll clarify what I can.

Resources:
Domain registrar for 12 Euros (about US$10) per year: http://www.gandi.net
Free dynamic DNS service, limited domains (only allows subdomains of dyndns.org, mine.nu, etc.): http://www.dyndns.org
Free DNS service, any domain, limited to 5 domains: http://www.zoneedit.com
Free DNS service, unlimited, but harder to work with:  http://soa.granitecanyon.com

[Tim Litwiller]

You explained that quite well Dan.  Another free DNS service that I use quite often is http://www.mydomain.com they just got thru a major upgrade and are working very well for me.

[Lloyd Keen]

Thanks for your help guys. I haven't seen mydomain.com before, they look quite good actually. My current domain is with gandi but I'm not game to transfer it to any of the free self help DNS servers just yet until I think I've got it sorted out. At the moment I'm gunna point the gandi Primary DNS record at soa.granitecanyon.com and if that seems to go OK then maybe I'll transfer the whole domain over to www.mydomain.com

[Charlie Brady]

Lloyd Keen wrote:

> Is it possible to remove the e-smith from
> ftp.e-smith.mydomain.xxx

It's possible, but unnecessary - that domain name is only available on your internal network, and can be abbreviated to just "ftp" on your internal network.

However ...

> BigPond Advance

Big Pond Advance, as well as a number of other cable providers, have assumed when they created their internal web pages that you will be perfectly happy to use their domain as your default local domain. To them, "www" is *their* web server, not your local web server (*). In order for you to adequately navigate their web portal, you need to configure both the server and your various workstations to use *their* local domain - vic.bigpond.net.au or whatever.

The e-smith server and gateway software is not currently equipped to conform to this unusual configuration requirement. See a recent post by Luke Drumm on the Advanced Forum for a likely workaround.

Regards

Charlie

(*) In case you were wondering, this is rather broken and highly antisocial.

) so I'm assuming that this would be the URL that you
> would have to type to access the ftp or web server. And while
> were on the DNS subject, would someone be able to explain the
> basics of DNS using a dynamic IP. My understanding is this: You
> purchase a domain name from a registrar and their DNS servers
> handle any requests for your domain. They may or may not be
> able to redirect any requests for your domain to another site
> (so far so good??). In order for me to handle the dns on my
> domain would it be a simple matter of going to my registrar and
> changing the Primary DNS server for my domain to my dynamically
> assigned IP address???? Somehow I don't think that it would be
> this easy. If someone could offer some words of wisdom I would
> very much appreciate it. Regards Lloyd