What servername type should I use?

Kevin Darcy kcd at daimlerchrysler.com
Tue Oct 29 21:59:49 UTC 2002

FF wrote:

> Hello!
> I'd like to run bind on my gateway computer. It's already installed, but I'm
> having difficulties configuring it, simply because I don't know what
> configuration type I should use.
> I don't know if I need to configure it as a primary nameserver, a secondary,
> a slaver, a master, a caching nameserver..? I'm lost!

You're getting lost in the terminology. Try to narrow your focus to the zone
level instead of the server level. A server that is the "primary master" for a
zone originates the zone data. A "slave" replicates that data from the primary
master (or perhaps another slave in a multi-tiered architecture). If you're
neither master nor slave for a zone, then the most you do with it is cache any
answer you get for names in that zone. So the 3 basic categories, on a
zone-by-zone basis, are: master, slave or caching (there are other zone types
as well -- stub and forward -- but those are basically just optimizations of
the "caching" zone category). When a nameserver is called a
"caching" nameserver or "caching-only" nameserver, generally what is meant is
that it is not master or slave for anything that anybody else cares about
(sometimes even a "caching-only" nameserver is configured as master for a zone
that maps its loopback address to a name).

So, armed with that clarification, what is it that you want to do? Do you want
to maintain your own DNS zone on your nameserver? If so, then be master for
that zone. You can still, of course, cache answers for everyone else's zones.
Or, is your domain already hosted somewhere else? Then maybe you want to be a
slave, so that you automatically get a local copy of your zone from the master
whenever it changes. If neither of those things are true, then don't make
yourself master or slave for any publically-available zones, and, by
definition, you have a caching-only nameserver.

> Here's what I'd like to do:
> I'd like to run bind on my gateway computer, and tell my LAN computer to
> request DNS information on my gateway. Is a caching nameserver what I need
> to set? I don't know if a "caching nameserver" would answer other LAN
> computers DNS requests...

For a caching-only nameserver, all you really need is a "hint" zone telling
your nameserver where the root nameservers are. Since the DNS database is
organized as a tree, once you know the root information, you can derive
everything else.

You can control what clients can query your nameserver through the allow-query
statement, which can take whole network prefixes as arguments. If your
"gateway" computer has multiple interfaces, you could also control query access
by telling the nameserver to only listen on an internal interface (with the
"listen-on" option).

- Kevin

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