iodined should add authority record pointing to ns.<topdomain> in each response

[guest]

My top.domain is controlled by multiple nameservers. I create a sub domain with name tunnel.top.domain and pointed it to only one name server. But when tunnel is established name queries for tunnel.top.domain are received on all my nameservers and speed is very slow.

After a few days of investigation I found that it is caused by follow issue:

1. iodine client sends first request to something.tunnel.top.domain
2. resolver sends request to the server that controls domain zone and receive not found reply with hint that ns.top.domain should be asked and that *.domain is contolled by ns.domain
3. resolver sends request to server that controls top.domain and receive not found reply with hint that tunnel.top.domain should be asked and that top.domain is controlled by ns.top.domain
4. resolver send request to server that controls tunnel.top.domain (yes. that's iodined) and receive reply, but idoned dones not say that tunnel.top.domain is controlled by him.
5. idoine client continue to send requests for something.tunnel.top.domain
6. resolver sends request directly to top.domain (because from previous request he known that top.domain is controlled by top.domain server)
7. Same as step 4.

If iodined daemon would add authority record pointing to ns.tunnel.top.domain resolver on step 4m resolver on step 6 will send request directly to iodined those removing workload from top.domain nameservers, removing a lot of duplicate requests from iodined if top.domain is controlled by multiple nameservers (in my case) and reducing response time (because of eliminating one point from dns chain)

I've attach a path.

[guest]

path for authority record and tests