Re: Caching Nameserver

[Art Ross <aross skyenet net>]

karlp ourldsfamily com wrote:

> Mark, You are correct. I have caching name servers all over the place at
> work, plus I do my own DNS at home, which my ISP queries twice daily for
> updates. In either case, the loopback IP is used. If I drop to another box
> on the network and do nslookup, it tells me the IP of the machine where
> DNS is found, but the response is the same and shows whether the IP is
> cached or not.
>
> Karl L. Pearson
> Senior Consulting Systems Analyst
> Senior Consulting Database Analyst
> karlp ourldsfamily com
>
> On Tue, 27 Feb 2001, Mark Knecht wrote:
>
> David,
>    You might also try just
>
> nslookup
>
>    This will take you into whatever name server you are using. You'll see
> the name & address of that DNS server. From there you can enter the ibm.com
> address, or any other address you want, for resolution.
>
>    You can also try
>
> nslookup - IP_ADDRESS
>
>    where the IP_ADDRESS is that of any DNS server you have access to, and
> you'll see that you're in that server getting your answers.
>
>    In Karl's answer below I think he was sitting on the name server and
> accessing it through the loopback interface.
>
> Mark
>
> -----Original Message-----
> From: karlp ourldsfamily com [mailto:karlp ourldsfamily com]
> Sent: Tuesday, February 27, 2001 11:00 AM
> To: Redhat Install
> Subject: Re: Caching Nameserver
>
> DNS (nslookup) returns the non-authoritative response when the name is
> cached locally because you've accessed it from your DNS server before. To
> verifty that, type
>
> nslookup www.ibm.com
>
> the output should look like:
>
> Server:  localhost
> Address:  127.0.0.1
>
> Name:    www.ibm.com
> Addresses:  129.42.16.99, 129.42.17.99, 129.42.18.99, 129.42.19.99
>
> Now do it again:
>
> nslookup www.ibm.com
>
> and now the response should look like:
>
> Server:  localhost
> Address:  127.0.0.1
>
> Non-authoritative answer:
> Name:    www.ibm.com
> Addresses:  129.42.18.99, 129.42.19.99, 129.42.16.99, 129.42.17.99
>
> That's because now the dns info is cached in memory and so the system is
> letting you know that it didn't go anywhere to find the info. The next
> time you log out and back in, you'll go through the same thing. Caching is
> only done during the current session and is stored in memory only. There
> isn't even a /proc entry for DNS lookup caching. So, don't ask if you can
> see it somewhere in a file. It isn't on disk in any form.
>
> Just a little tutorial for the interested.
>
> Karl L. Pearson
> Senior Consulting Systems Analyst
> Senior Consulting Database Analyst
> karlp ourldsfamily com
>
> On Mon, 26 Feb 2001, Art Ross wrote:
>
> Chan Chow Chin, David
>   I implemented what you suggested and it appears that I might have a
> working caching nameserver for my local home network.  I'm a bit confused
> about my output from an 'nslookup einstein.linuxindayton.com'.  This is one
> of the machines on my home network and has an IP of 192.168.1.3.  In fact
> this is the nameserver.  I've included my name.conf and the output from the
> nslookup command.
>   Any help you can provide will be greatly appreciated.  This DNS stuff is
> very interesting.  Unfortunately,  my experience is about two hours so far
> and hasn't proven to be adequate.  The named.conf attachment is obvious.
> The output file is the output from the nslookup command.
>   My big question is the following; "Is the DNS really working?"  If so,
> why is my machine being assigned the IP for the DNS of my ISP?
>   Thank you for any assistance you can provide.
>   Art
>
> "CHAN Chow Chin, David" wrote:
>
> > well, I think you're missing your forwarders in your named.conf file.
> > Inside named.conf, under the "options" section, insert:-
> >
> > forward first;
> > forwarders {
> >         ip.of.dns.1;
> >         ip.of.dns.2;
> > };
> >
> > eg:
> > forward first;
> > forwarders{
> >         161.142.2.17;
> > };
> >
> > hope it helps. :),
> > CHAN Chow Chin, David
> >
> > P.S. Oh! dont' forget to restart named.
> >
> > -----Original Message-----
> > From: Art Ross [mailto:aross skyenet net]
> > Sent: Monday, 26 February, 2001 12:43 PM
> > To: redhat-install-list redhat com
> > Subject: Caching Nameserver
> >
> > I'm trying to get a caching nameserver setup and operating on my home
> > network.  I have downloaded an installed the rpm's from Redhat.  These
> > included 'bind' and 'caching-nameserver'.  Using linuxconf, I've added a
> > zone for my home network.  When I test it using 'nslookup', it tells me
> > that it cannot find host/domain for the nameserver's ip.
> >   Also, when I try an nslookup on any of my machines on the home
> > network, I cannot find them.  What have I missed?  Will a caching
> > nameserver eliminate the need for me to keep all the hosts files on
> > every machine current?
> >   Any help is appreciated.
> >   Art
> >
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I'm back and having done by research and reading as all of you really
indicated, I have a DNS working on my home network.  One of you stated they
had worked with the DNS HOWTO.  Well, that was a wonderful reference.  Under
the direction of the author in this reference, I managed to get a caching
nameserver setup.  Feeling good about that accomplishment, I braved setting up
my own domain server behind my Linux router.  That went very well under the
direction of the DNS HOWTO.
  Now I'm studying a couple of my references to actually understand what I've
done.
  Thank you again for all of your assistance.
  Art