[dns-operations] Minimalistic DNS server for SOA and AXFR

[Anand Buddhdev]

Hello DNS gurus,

I'm writing a minimalistic DNS server (in python, using the dnspython 
module), whose purpose will simply be to provide AXFR for a fixed set of 
zones. The clients will be BIND and/or NSD. It will send NOTIFY messages 
to the clients, and provide (some) responses.

As far as I can see, my small DNS server needs to do the following:

1. Listen on UDP/53, and:

1a. return REFUSED responses for any zones I haven't loaded;

1b. return NOTIMP responses to queries other than SOA; and

1c. return a NOERROR response for zones I have, with the SOA record in 
the answer section, setting the AA bit. Do I need to fill the authority 
section too?

2. Listen on TCP/53, and:

2a. return REFUSED responses for any zones I haven't loaded; and

2b. return NOTIMP responses to queries other than AXFR; and

2c. return the zone in response to AXFR.

Have I missed anything obvious?

Regards,

Anand