dns cache

[Kevin Darcy]

Martin Trèka wrote:

> Hello,
> I am running BIND (8.2) on a LAN for resolving names on that LAN only.
> Do I have to include directive
>
> zone "." {
>         type hint;
>         file "named.ca";
> };
>
> in the conf file for the names of LAN hosts being cached ?

> What's the PRECISE meaning of the named.ca file (which includes NS and
> Arecords for ROOT servers, that i don't need on the LAN) ?

To put it succinctly: if you have default forwarding configured, you don't
need a hints file; but in the absence of default forwarding, your server
will need *some* source of root information in order to resolve recursive
queries in domains it does not explicitly recognize. Hints files are the
usual way of providing this root information, but other potential ways
include becoming a stub, slave or master to a root zone (note that all
three of these alternatives incur zone-transfer overhead, and the last two
are only feasible for internal root zones). If named has no way to resolve
such unrecognized-domain queries, it responds to them with ugly "server
failed" errors, and complains a lot in the logs.

Also, you should only use a hints file if your server has access to the
entire network that the root servers in the hints file serve; in
particular, don't use an Internet hints file unless your server has
Internet access. Otherwise, when you get a query in an unrecognized domain,
your server will just waste time and resources, vainly trying to resolve
the query using unreachable root servers.


- Kevin