name server vs client

[Julia Goolia]

johnathan,

thank you for your response!  allow me to clarify my question.  I have
DNS server running on a machine which has an IP that can be accessed
from the internet.  my understanding of the "DNS CLIENT" on that
machine is it indicates the proper DNS server to connect to when
resolving names on that machine (like if I did "telnet www.google.com"
then it would use the "DNS CLIENT" to resolve the "www.google.com"
address).  however, i would also like to be able to add zones and
records for domain names on the DNS SERVER running on that machine. 
when queries arrive at that machine about these particular domains, I
want the DNS server to respond with the records I added, and NOT look
them up via the DNS client.

i'm think now (after your explanation) that the "DNS CLIENT" is quite
unrelated to this desired functionality.  somebody on the internet
will connect to port 53 of that machine and ask a query and get a
response... i don't think the server would then use the client to look
up the query... would it?  what about queries about zones that that
machine is not authoritative for... who does that machine ask after it
realized it is not authoratative for a particular query (i assumed
this is what the "DNS CLIENT" is for).

well i think there is a question in there somewhere...
cheers,
julia


Jonathan de Boyne Pollard <J.deBoynePollard at tesco.net> wrote in message news:<bhb9sd$1mn$1 at sf1.isc.org>...
> JG> What do I use as the DNS CLIENT?  Right now, the first server 
> JG> is 127.0.0.1 and names are getting resolved just fine.
> 
> The (relevant) DNS client is the library that is (statically or dynamically)
> linked into your applications programs.  The configuration directive listing
> 127.0.0.1 is denoting the IP address of a DNS _server_ to which your DNS
> client sends its queries.  You are not configuring what you "use as the DNS
> client".  You are configuring _what your DNS client uses_ as the proxy DNS
> server.
> 
> What you "use as the DNS client" is, in fact, not easily configurable. 
> Indeed, for applications that statically link to the library (a rarity, but a
> possibility), it is impossible to configure without re-linking those
> applications with some other library.
> 
> JG> There are two other servers, are my ISP's name servers.  
> JG> Should they go first?
> 
> There's not actually much point in listing them in your DNS client's
> configuration at all.
> 
> Since 127.0.0.1 is by convention an IP address of the loopback network
> interface, the implication is that you have a proxy DNS server running on your
> machine.  The primary point of configuring your DNS client with a list of
> several proxy DNS servers is for fallback in the event of a server outage or a
> partial loss of network connectivity.  However, since the DNS server is
> running on the very same machine, most of the occasions where your DNS server
> will suffer an outage will be those occasions where the applications that
> would require the services of that server most probably will be suffering an
> outage as well.  (-:
> 
> You might want to list your ISP's DNS servers in your _server's_ configuration
> file, as forwardees, but that is a different kettle of fish entirely.
> 
> JG> I try to query the server from an external source [...]
> 
> An "external source" won't be able to communicate with a service that is
> listening on a loopback IP address.  Is 127.0.0.1 the only address on which
> your DNS server is listening ?  What IP address did you send the query to ?
> 
> JG> the answer I get seems to be from the client [...]
> 
> DNS clients don't listen on IP addresses.  If you received a response, it was
> from a DNS _server_.  Perhaps it was the one that is also listening on
> 127.0.0.1.  Perhaps it is also a correct response to the query that you sent. 
> Please show us the query that you sent and the response that you received. 
> Show us the actual data, not the conclusions that you have drawn from them.