some networking questions, I'm slightly confused

Gregory Nowak gnowak1 at
Wed Dec 5 22:56:49 EST 2001

Thanks for the info even though I knew 99% of that.
I will be in touch if I need more help.
Again, thanks for a very good explanation (it's certainly better then I could've done (grin)).

On Wed, Dec 05, 2001 at 08:19:57PM -0700, Darrell Shandrow wrote:
> Hi Greg,
> I have stayed out of this until now because I haven't really had any time 
> to respond properly.  My days are usually quite long lately.  Anyhow, I am 
> a sys admin for a regional ISP; perhaps, I can help you.
> A domain is registered through a registrar like Network Solutions or 
>  When the domain is registered, part of the required 
> information includes the IP addresses for the primary and secondary name 
> servers.  This information is then added to what are known as the root 
> servers, which tell the entire world which primary and secondary name 
> servers know how to answer lookup questions about your domain.  In other 
> words, the root servers delegate authority to the specified primary and 
> secondary name servers to answer questions concerning your domain 
> name.  You could run one or both of these name servers yourself or have 
> someone else do DNS.  It sounds like you are having someone else do primary 
> and secondary DNS.  As I'm sure you already know, DNS is the domain name 
> system, which points domain names to IP addresses, and which allows us to 
> do neat things like browse to and send mail to 
> nu7i at instead of having to know all kinds of awful IP addresses 
> just to perform the simplest of functions on the Internet.  So, DNS points 
> a domain name to an IP address, but how does it work?  DNS information 
> about a domain name is handled by name servers in the form of zone 
> files.  Your domain exists as a zone file on the primary name server, and 
> the secondary name server is usually set up as a slave to the primary.  In 
> other words, the secondary name server gets its information (the zone file) 
> from the primary name server and holds onto it, just in case the primary 
> name server is unavailable for some reason.  The domain name system is 
> really a very large, world wide distributed database.  A domain name 
> contains various types of information which is managed in the form of 
> various types of records.  The first type of record is SOA, which stands 
> for start of authority.  This just specifies your primary and secondary 
> name servers.  You see, if things were set up a certain way, your primary 
> and secondary name servers could actually delegate authority for your 
> domain to still other name servers, but this is not common 
> practice.  Another important record type is the A record.  This is the 
> address record, and your domain could have multiple A records, depending on 
> how many subdomains you have set up.  For example my domain name servers 
> have an A record for which points to  There is 
> also another A record for, a subdomain, which also 
> happens to point to the same IP address, though it could just as easily 
> point to another IP address.  Another somewhat related record type is a 
> CNAME, which stands for canonical name.  These records are used like 
> aliases to point subdomains to other domains.  For example, I did use a 
> CNAME record to point to, which means it also 
> has the IP address  Yet another important record type is 
> the MX record.  MX stands for mail exchanger.  E-mail software uses these 
> records when figuring out how to deliver e-mail on the Internet.  These 
> records, numbered by priority, tell mail delivery software where mail 
> should go when destined for a particular domain.  For example, my first MX 
> record priority for (which is MX 10) points to 
>  That is ultimately pointing to the Sendmail server 
> which runs on the IP address  But, again, this could have 
> just as easily pointed to any Sendmail server which was configured to 
> accept and deliver mail for the domain.  Additional MX records 
> can be defined so that, if the server specified in the first priority MX 
> record is unavailable for some reason, mail delivery software will try a 
> second, third, fourth and so on server until it can deliver the mail.  I 
> could, if configured properly, have a MX 20 pointing to yet 
> another Sendmail server, which would be able to receive mail for 
> in the absence of the primary mail server.
> Finally, there is reverse DNS.  This does the reverse of the domain name 
> system; it translates IP addresses back to domain names.  You definitely 
> want to have your DNS administrator set this up for your domain, because 
> certain FTP sites, web sites and other types of services on the Internet 
> use reverse DNS information for security purposes; they want to see that 
> your forward DNS and reverse DNS point to the same place, or they may also 
> want to verify that you have a domain which is or is not registered in a 
> certain part of the world.  In my example, performing a nslookup on the IP 
> address will tell you that it reverses to, 
> which is a valid subdomain pointing to that same IP address.
> Anyhow, this will either help you or confuse you.  Please let me know if I 
> can help you with specifics.
> Regards.
> At 06:38 PM 12/5/2001 -0600, you wrote:
> >Well, I'll actually be running a mail server for the building in which I live.
> >Instead of being regularly payed, my current connection will be free, and 
> >I'll get a second free connection
> >They're running t1 over here through this HP networking gizmo that
> >plugs into the phone jack, and has an rj45 jack on it.
> >
> >
> >The reason I'm asking about the dns stuff is because
> >when I told the guy that I've looked at the mail admin docs, and am 
> >seriously considering running the server,
> >his response to me was:
> >"so, I'll need to get you a domain with primary and secondary dns servers."
> >I said yes to this, but am carious about how his dns servers will know 
> >where I exist
> >since he didn't ask for the name of my box.
> >I guess when he tells me he's got things set up,
> >my first question to him will be,
> >"what name do the dns servers know my machine by?"
> >
> >He's macroslop licensed, but not meaning to brag,
> >I get the impression that I may know more then he does without a license.
> >
> >In case some of you reading my post now are remembering a few of my other 
> >posts, I decided
> >that getting my own domain name wasn't worth it.
> >He said that I could run a small web server here if I want. So, I don't 
> >think he'd
> >have a problem with me running it as http://mybox.domain.
> >
> >This whole thing started when I got my service, and he came here to get it 
> >all setup.
> >Not only was he impressed that I was the only one in the building so far 
> >running anything other then windblows, but that it was Linux.
> >After my configuring tcp/ip both in windows and in Linux while he just 
> >watched me do it and gave me my ip address and all the other stuff,
> >I asked if I would get a mail account.
> >He said no, because there is no body to run one yet.
> >Then he tentatively asked if I would be willing to perhaps do it, I said 
> >I'd read the mailadmin docs and think about it,
> >and you know the rest.
> >
> >He's also looking to hire someone to run apachee.
> >But, I'm not touching that for now (grin).
> >Sorry for the long and personal post, but since Geoff asked,
> >I figured that some other people on this list may be wondering
> >why I'm asking theese questions, some of which may sound
> >dumb, but are for the most part so that I could make sure that what
> >I know is actually correct.
> >Greg
> >
> >
> >On Thu, Dec 06, 2001 at 09:29:48AM +1000, Geoff Shang wrote:
> > > On Tue, 4 Dec 2001, Gregory Nowak wrote:
> > >
> > > > 1. Say there is a primary and secondary dns servers on a domain 
> > called mydomain.
> > > > Say also that there is a machine called mybox.
> > > > Also, I have ip addresses for primary and secondary dns servers on 
> > mydomain.
> > > > Assumming all of the above, and assuming that I have permission to 
> > officially be on mydomain which is a valid internet domain,
> > > > what do I do on mybox so that it would be resolvable
> > > > as mybox.mydomain on the net?
> > >
> > > Nothing.  It's the primary and secondary DNS servers that control how your
> > > host is resolved, not your box.  As long as mybox has the IP address that
> > > and think it has, you should be good to
> > > go.
> > >
> > > > 2. Say that I have to nics with 2 static ip address for the outside 
> > world.
> > > > How do I set things up so that my box would use both
> > > > nics for outside access instead just either one nic or the other?
> > >
> > > As Chris said, what comes in where will depend on what address it is sent
> > > to.  What goes out where depends on a few things.  If you want to use one
> > > interface to access a particular host or network, you can set up a route
> > > accordingly.  If you want to access everything with both, you might be able
> > > to put 2 default routes (i've seen it done but don't know if it works and
> > > if it's supposed to work).  I saw you've been looking at bonding which
> > > might also work, but I don't know about it.
> > >
> > > Can I ask, why you have 2 NICs?  Is it just to get 2 addresses or are you
> > > connected to 2 networks?
> > >
> > > Geoff.
> > >
> > >
> > >
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