Wildcard DNS with BIND

I'm trying to setup BIND so that it catches any and all requests made to it, and points them to a specific set of NS servers, and a specific A record.

I have around 500 domains, and I'm adding new ones at the rate of 10-15 a day, so I don't want to explicitely add a zone for every domain.

My current setup is:
in my named.conf, I have a view (named external) with the following zone in it:

zone "." {
        type master;
        file "ext.zone";
};

This matches all requests.

ext.zone is:

$TTL    3600
@       IN      SOA     . root.nsdomain.com. (
                              1         ; Serial
                         3600         ; Refresh
                          300         ; Retry
                         3600         ; Expire
                         300 )        ; Negative Cache TTL



        IN      NS      ns1.example.com
        IN      NS      ns2.example.com

ns1     IN      A       192.0.2.4
ns2     IN      A       192.0.2.5

*.      IN      A       192.0.2.6

so, the goal is:
for all NS requests, return ns1.example.com and ns2.example.com
for all A requests, except where it is ns1.example.com or ns2.example.com, return 192.0.2.6. For ns1.example.com return 192.0.2.4, for ns2.example.com return 192.0.2.5.

This almost works, the only problem is that when I do a dig, I get:

dig @localhost somedomain.example

; > DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 > @localhost somedomain.example

; (1 server found)
;; global options:  printcmd
;; Got answer:
;; opcode: QUERY, status: NOERROR, id: 37733
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;somedomain.example.                        IN      A

;; ANSWER SECTION:

somedomain.example.         3600    IN      A       192.0.2.6 // as expected

;; AUTHORITY SECTION:
.                       3600    IN      NS      ns1.example.com. // expected, I don't know if the "." at the start is bad, though.
.                       3600    IN      NS      ns2.example.com. // see above.

;; ADDITIONAL SECTION:
ns1.example.com.  3600    IN      A       192.0.2.6 // not expected, this should be 192.0.2.4
ns2.example.com.  3600    IN      A       192.0.2.6 // not expected, this should be 192.0.2.5

How do I fix this? Am I doing something horrible? Is there a better way to do this?

Answer

Your origin for the zone is . per your configuration. You are creating records for ns1. and ns2. instead of ns1.example.com. and ns2.example.com. Since ns1.example.com and ns2.example.com aren't defined, they are matched by the wildcard.

EDIT: here's an edit of your config and zone:

zone "example.com." {
        type master;
        file "ext.zone";

};

ext.zone:

$TTL    3600
@       IN      SOA     ns1 root (
                              1         ; Serial
                         3600         ; Refresh
                          300         ; Retry

                         3600         ; Expire
                         300 )        ; Negative Cache TTL


        IN      NS      ns1
        IN      NS      ns2
        IN      A       192.0.2.6


ns1     IN      A       192.0.2.4

ns2     IN      A       192.0.2.5

*      IN      A       192.0.2.6

Everything in the zone is relative to the zone name in the named configuration, so adding a second zone just points to the same file:

zone "example.net." {
    type master;
    file "ext.zone";

};