Unwanted ISDN connections caused by BIND

[Jim Reid]

>>>>> "Brian" == Brian {Hamilton Kelly} <bhk at dsl.co.uk> writes:

    Bernd> provider, exactly in the moment when BIND starts. Also later, in
    Bernd> irregular intervals, the machine makes unwanted ISDN connection. I
    >> 
    >> This is to be expected. Your name server has to talk to other name
    >> servers, especially if it has to resolve external names. What you
    >> could do is configure your PPP/ISDN code to only let DNS traffic out
    >> if the serial line is already up. [OTOH, that might stop external
    >> lookups from working, zone transfers might fail, valid zones could
    >> expire, etc, etc.] Another approach would be to keep the line up for
    >> one PPT-charging-unit after the DNS lookup in the hope that someone
    >> generates some off-site traffic - web access or whatever - soon after
    >> they'd looked up the external name.

    Brian> This is actually BIND trying to refresh its cache vis-a-vis
    Brian> the root nameservers, SFAICT.  ....

Indeed. And it may well be making other external lookups too: for
instance if it's forwarding queries or slaving zones.

    Brian> once BIND starts, it does a dial-on-demand trying to
    Brian> contact each of the IP numbers for the 14 (? --- I haven't
    Brian> counted lately) root nameservers.  (Well, strictly speaking, 
    Brian> it just tries to contact one of them, I guess; but if my
    Brian> D-o-D is inhibited, it tries to contact each in turn ---
    Brian> and goes on and ON, until I re-enable the  D-o-D.)

Absolutely. The name server uses the info in the root.cache file to
find the real root name servers when it starts. So if you won't let it
contact server A in that file, it tries server B and so on.

    Brian> Once BIND is running, it can go a week without my having
    Brian> made another connection to the outside world.

This is inconsistent with what you seem to be saying below. If your
name server is forwarding queries to your ISP's server, presumably
those queries will be bringing up the ISDN link too if they're for
names that aren't in your name server's cache already.

    Brian> Obviously with a D-o-D connection such as this, I'm serving
    Brian> up my internal LAN, and use a forwarders line to specify my
    Brian> ISP's nameservers