NFS help

[Mark Knecht]

On 8/27/05, brad.mugleston at comcast.net <brad.mugleston at comcast.net> wrote:
> 
> On Sat, 27 Aug 2005, Mark Knecht wrote:
> 
> >
> > mark at flash ~ $  nslookup www.cisco.com
> > Server:         204.127.199.8
> > Address:        204.127.199.8#53
> >
> > Non-authoritative answer:
> > Name:   www.cisco.com
> > Address: 198.133.219.25
> >
> > Following that I ask my firewall for the same info. Notice that the IP
> > address of the server (linksys) is 192.168.1.1:
> >
> > mark at flash ~ $  nslookup www.cisco.com linksys
> > Server:         linksys
> > Address:        192.168.1.1#53
> >
> > Non-authoritative answer:
> > Name:   www.cisco.com
> > Address: 198.133.219.25
> >
> > mark at flash ~ $
> >
> > The firewall gives me the same address as the outside default DNS server.
> >
> > If you want to use DHCP then the fireall hands out the address and
> > puts it in the DNS server it runs. Your internal machines are remapped
> > to go there (/etc/resolv.conf) and they get the addresses from it.
> >
> > Geez....it seems so simple maybe I should be using it. ;-)
> >
> > Hope this helps,
> > Mark
> >
> Mark,
> 
> I am stepping out on a limb here but I bet your linksys isn't a
> DNS server but is acting as a gateway to a real DNS when
> you request a DNS service from it.  It probably takes a lot more
> memory than whats in that linksys to hold all the addresses a DNS
> has......
> 
> Brad
> 

Brad,
   Nope. Not true. My LinkSys router is acting as a DNS server, but is
'authoritative ONLY for machines on my network.

   You are correct that there are far too many addresses in the world
for my little router to handle, but that's true for almost every DNS
server out there. This is all handled by the DNS protocol and what's
called 'caching'. If my little router doesn't have an address then it
has an address in it of another DNS server that it can get it from.
However if it does have the address then it doesn't have to ask the
outside server to resolve it. If you look at your router (like my
LinkSys) then you will se it is probably getting a DNS server address
from your ISP automatically. When my DNS server doesn't know the
answer to a question it just passes the question to the other,
outside, DNS server to get the answer.

   Now, as for your 'internal' addresses, most probably 192.168.1.XXX,
those addresses are unrouteable and therefore the external, outside,
DNS server cannot know that your machine with name 'basement' has been
given address 192.168.1.100 by your DHCP server. Those "name to
address" translations must be done by a machine on your network since
I would have my own machine 'livingroom' at address 192.168.1.100 here
on my network. We don't want confusion.

   Again, the internal DNS server is only responsible for your domain.
For these machines your DNS server will be considered 'authoritative'
for names and addresses on your network, but 'non-authoritative' for
addresses not on your network. (The world...)

Hope this helps,
Mark