stub zones

[Kevin Darcy]

Tim Maestas wrote:

> When you set up a zone of type stub, when the zone is loaded what method
> does named use to get the NS records and any corresponding glue from the
> server listed as master?  In the zone file that is created on the stub
> server after starting the server, it says:
>
> ; zone 'foo.com' first transfer
> ; from 192.168.1.1:53 (local 192.168.1.2) using AXFR at <date>
>
> This would lead me to believe that it used AXFR to transfer the records.
> But AXFR would transfer the whole zone, not just the NS records.  Besides
> which I see nothing in the master server's logs to indicate any
> kind of zone transfer took place.  And if I don't allow the stub server's
> IP in
> allow-transfers, it still is able to get the NS records.  Is it just doing
> an SOA query on the master and getting the NS and glue records from that?
> If this is what's happening, why does it say "using AXFR" above?

I think it's just a case of a misleading comment. The named-xfer code that
generates this is:

                        fprintf(dbfp, "; from %s:%d (local %s) using %s at
%s",
                                t, ntohs(sin.sin_port),
                                inet_ntoa(local.sin_addr),
                                (methode == ISIXFR) ? "IXFR":"AXFR",
                                ctimel(tt.tv_sec));

As you can see (you don't have to be a programmer to comprehend this, I don't
think), it's reporting everything not an IXFR as an AXFR, not bothering to
check first whether the mode is "stub" or not; the "stub" versus
non-"stub" distinction doesn't really kick in until a little later in the
code, in the main send-query-and-parse-response(s) loop of the program.

For completeness, the comment should probably be improved to distinguish
"IXFR" from"AXFR" from "ZXFR" from "SOA/NS" (for stub zones).

While looking at this, I stumbled on (what I consider) a bug wherein
named-xfer in "stub" mode performs an additional -- that is to say, second --
SOA query before the NS query, even in situations where it's unnecessary.


- Kevin