[lug] strange name resolving/ftp

[rm at mamma.varadinet.de]

On Sun, Jun 10, 2001 at 02:05:06PM -0600, D. Stimits wrote:
> ...
> > 
> > I'm a bit ignorant of nsswitch.conf. For background, I do not run DNS or
> > bind on any machine. All machines point towards the ISP's DNS (and the
> > firewall blocks any DNS conversation with any machine other than those
> > of the ISP; I see lots of logged outside parties trying to reach my DNS
> > ports, probably for exploits). This machine has only an ethernet card,
> > and the machine it points to is not connected to the internet at the
> > time of test (it uses ppp dialup). But I think the relevant lines you'd
> > be interested in are:
> > hosts: files nisplus dns
> > ethers: files
> > netmasks: files
> > networks: files
> > protocols: files nisplus
> > rpc: files
> > services files nisplus
> > aliases: files nisplus
> ...

That looks ok to me. Do you actually use NIS services ? Otherwise it might
make sense to have a host entry 'files dns'.

> Additional note I forgot. I want the machines I use to consult
> /etc/hosts first, and then the outside DNS at the ISP. 

That's what the above configuration should do. 
One tool i often use when debugging DNS problems is ethereal. I just run
tcpdump while i use DNS and inspect the dump file with ethereal. You can
see what query went to whome and who answered with what. I recently had
a server come down to a crunching halt when the ISP decided that the DNS
server should answer queries for 'localhost' with the _server_ IP rather
than with 127.0.0.1 .... do i need to tell what OS the server was running ;-)

> About 75% of the
> time the outside DNS is not available, but that's fine with me (I have
> to hang up the phone sometimes). Internal names resolving is the main
> thing, I'm trying to test client server software, as well as using the
> two as a partial backup of each other.

I found that it's often easier to keep a consitent DNS with one server in
the internal net that's forwarding queries to the ISPs server. You don't have
to maintain a lot of host files and can quickly change settings in one place.
If you are offline most of the time a server like  DNRD, a proxy name server
that'll forward all queries to an external server but that will also cache the
results and hance will answer queries even if the connection to your ISP is down.
(http://members.home.com/garsh/dnrd/).

Ralf