Hi Tony, On 16-May-00, you wrote:
> I gather that, on the internet, there are sites called DNS Servers (or
> similar) which translate the www.fred.com URL's to their numeric
> equivalents.
> It occurred to me that these must have a list of all URL's. Would
> it be possible for a voyager to have a function which would
> interrogate the DSN Server and return a list of all URL's which match
> a wild-card string?
Crikey, you're a bit far off the mark here I'm afraid mate :)
You're right in saying that fundamental to the Internet these days are DNS
servers, which translate a *hostname* (NOT a URL - a hostname is something
like "foo.bar.com", "www.demon.net", "ftp.test.org" and a URL is
"http://www.demon.net/blahblah/blah") to an IP address. However, there is
NOT a DNS server which contains a list of all URLs. There are many
hundreds of thousands of DNS servers scattered around the world, each one
often only holding information for one or two domains What happens is that
when you register a domain (e.g. blah.co.uk), you specify a "primary" and
"secondary" server which will contain the domain information for that
domain. You can find this out for any domain using a whois lookup:
8.Programs:Comms/Internet/NetConnect3/AmiTCP/usr/tim>whois demon.net
Whois Server Version 1.1
Domain names in the .com, .net, and .org domains can now be registered
with many different competing registrars. Go to http://www.internic.net
for detailed information.
Domain Name: DEMON.NET
Registrar: NETWORK SOLUTIONS, INC.
Whois Server: whois.networksolutions.com
Referral URL: www.networksolutions.com
Name Server: NS0.DEMON.CO.UK
Name Server: NS1.DEMON.CO.UK
Name Server: NS2.DEMON.NET
Updated Date: 29-dec-1999
What this says is that if you want to find out information about hosts under
demon.net (e.g. ftp.demon.net, www.demon.net, blah.demon.net) you should go
and ask the host ns0.demon.co.uk first and if that doesn't work for some
reason try ns1.demon.co.uk followed by ns2.demon.co.uk. It's possible that
ns0/1/2.demon.co.uk ONLY contain information for demon.net and no other
domains.
Anyway, once you know the DNS server for "thedomain.com" you can look up
information, for example querying it to ask the IP address of
"blah.thedomain.com"
However, for 99% of dialup users they don't actually go through all this,
which is probably where your confusion has come from. You probably just
use one or two name servers given to you by your ISP. These are forwarding
nameservers and will answer queries for ANY domain but not because they
have all the information in the world! They simply go and look for it from
the appropriate server and then give you the answer. It makes things a lot
simpler and faster that way.
By the way, in case you wondered, I manage two DNS servers :)
> Quite often I know roughly what a URL should be, but close doesn't
> count. It would be good to be able to enter the string www.some*
> into the URL box and get a pop-up menu with the answers. Of course
> there would have to be a match limit or www.* might be a little bit
> slow.
What you need is a search engine :) I'm not sure if you can enter wildcards
*quite* like that into AltaVista, but you can certainly limit searches to
certain domains/hosts. I use it for much the same reason that you say. For
example, say I can remember that a site about mashed potatoes is hosted on
web2.blah.com but I can't remember the actual address, I'll go to AltaVista
(www.av.com) and enter:
"mashed potatoes" +host:web2.blah.com
and that should do the trick. Also, go to AV and instead of just blindly
entering a search, go and read all the documentation on there about
searching and you'll find all sorts of powerful things you can enter into
the search box to help you get what you want.
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