Nate wrote regarding 'Re: [OT] Who says dub dub dub ?' on Sun, Mar 05 at 17:21:
> Technically speaking, in the nameserver you can have A records (or AAAA 
> records if it's an IPv6 address you're going to resolve to), and NS 
> records.  Everything is hierarchical in DNS, so if you don't define a 
> nameserver in an NS record for "www.natetech.com" so you can have an A 
> record for a host named "anycomputer.www.natetech.com", you'd default 
> back to the higher-level nameserver record, in this case, 
> "natetech.com"'s NS record.

You can have an A record and a NS record for the same FQDN.  Setting
up internal.dannysauer.com to both delegate to a new domain server and
to resolve to the IP address is no different than setting
www.dannysauer.com and dannysauer.com to both have the same A records,
just because they're one level below the com space doesn't make them
any more special than being two levels down.  Sure, you probably don't
want to do both on the same server, but since the NS record is just a
means of delegating authoritative lookups to a new machine, it'd be
silly to claim to be be authoritative for the address and say that
someone else is authoritative at the same time.  I do sometimes put NS
and MX records on the same server, though...

> It's about a 2 second job to make an A record for "natetech.com" as well 
> as "www.natetech.com", or any other combination.

Two seconds?  You type slow. :)

> You can also use CNAME records (aliases), which point to other names: 
> Thus, any arbitrary name can point to another.

It's worth noting, in case anyone's using a random discussion on the
piclist as their sole definitive reference point for DNS setup
information, that you don't ever want to use a hostname defined as a
CNAME in an MX record.  It's somethign spammers do, and it's suggested
against in the RFCs.  Lots of mail servers will reject mail going to
or coming from a mail exchange whose name is resolved via CNAME.
Otherwise, feel free to experiement.  That one particular oddity won't
always be obivous in experimentation, though...

> DNS is perhaps the most resilient and fastest, distributed world-wide 
> database ever created.  And all done by keeping it as utterly simple as 
> possible, without being too simple to do the job.

DNS is a really awesome system.  Probably because theer's almost no
money in it, so no company has tried to screw it up in order to make
themselves more money.  Well, except for the time when Internic added
a default record in the .com level so any mistyped / down domain name
automatically redirected to their search portal.  That went over
*real* well.

> You can also provide usernames and passwords for FTP in most modern 
> browsers.  Many geeks even miss this feature: 
> "http://user@ftp.natetech.com" --> This would define the username, but 
> not the password.

You forgot about "ftp://user:password@ftp.natetech.com:21/".  It's
important to see that form if for no other reason than to note that,
when you're using a web browser for FTP, that's the URL stored in your
history.  Probably.  It may prompt you for a password, but that's
ultimitely the URI it's looking for.  That's what gets passed to a
proxy, as well.  People get confused about that colon in there, since
there's also a colon used to separate the FQDN (which, to respond to
another post, is *not* the hostname - the hostname is "ftp" in this
example, and only "ftp".  The Fully Qualified Domain Name is something
else which *contains* the hostname as its leftmost component) from the
port.  The @ sign ensures that the username:password is distinct from
FQDN:port.  I use that on links to anonymous / guest FTP sites
sometimes, especially internally.

> > So there's rarely any need to actually *say* either the "http://" or the
> > "www." when giving a domain name verbally.
> 
> I find this not to be true for amateur-created sites.  They're either 
> hosted on virutal servers, where the web server wasn't set up (properly) 
> to answer for both the domain name used as a host name, or the person 
> setting them up doesn't even realize that both can be pointed at the IP 
> address of their machine.

There's a third case - sometimes the machine doesn't *have* a "main"
web site, and just hosts several name-based hosts on a particular
server / IP.  Since there's no logical value to fill in for the
subdomain's A record in that case, it's just left blank.  Everyone who
does that is not neccesarily a novice. ;)  Though really, I'd still
claim that to be a silly mistake - the site should provide some kind
of placeholder notifying the user of their error, both at the top
level and under "www" as the case dictates.  Some admins are not very
user-focused, though, and get a kick out of effectively saying "screw
you" to any misinformed user.  But there's a whole other debate on
whether admins like that are truly competent (I think I've already
made *my* position on that clear, though)... :)

--Danny, who maintains quite a few large DNS installations
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