name server vs client

[Danny Mayer]

The DNS CLIENT that I think you are referring to is a Windows System
Service that Microsoft introduced in Windows 2000. It is supposed to
cache answers to lookups when resolving queries. I always turn it off
since that means that negative answers or bad answers take longer to
clean out. I believe that Sun originally implemented this scheme and
thought it was a good idea. If you are talking about Windows, the
addresses for the DNS servers to perform lookups are either in the
registry if it has a fixed address or they are supplied by the DHCP
server supplying it with a leased IP address. The "DNS CLIENT"
has nothing to do with it.

Danny

At 03:15 PM 8/13/03, Julia Goolia wrote:
>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.=20
>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 n=
>ews:<bhb9sd$1mn$1 at sf1.isc.org>...
> > JG> What do I use as the DNS CLIENT?  Right now, the first server=20
> > JG> is 127.0.0.1 and names are getting resolved just fine.
> >=20
> > The (relevant) DNS client is the library that is (statically or dynamic=
>ally)
> > linked into your applications programs.  The configuration directive li=
>sting
> > 127.0.0.1 is denoting the IP address of a DNS _server_ to which your DN=
>S
> > 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.
> >=20
> > What you "use as the DNS client" is, in fact, not easily configurable.=20
> > 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.
> >=20
> > JG> There are two other servers, are my ISP's name servers. =20
> > JG> Should they go first?
> >=20
> > There's not actually much point in listing them in your DNS client's
> > configuration at all.
> >=20
> > 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 outa=
>ge 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 th=
>at
> > would require the services of that server most probably will be sufferi=
>ng an
> > outage as well.  (-:
> >=20
> > You might want to list your ISP's DNS servers in your _server's_ config=
>uration
> > file, as forwardees, but that is a different kettle of fish entirely.
> >=20
> > JG> I try to query the server from an external source [...]
> >=20
> > An "external source" won't be able to communicate with a service that i=
>s
> > listening on a loopback IP address.  Is 127.0.0.1 the only address on w=
>hich
> > your DNS server is listening ?  What IP address did you send the query =
>to ?
> >=20
> > JG> the answer I get seems to be from the client [...]
> >=20
> > 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.=20
> > Please show us the query that you sent and the response that you receiv=
>ed.=20
> > Show us the actual data, not the conclusions that you have drawn from t=
>hem.