How do I connect my local DNS server to provider's?

Question

I have bought a domain name from GoDaddy and I have my old PC acting as a server. I want to setup my DNS server that will be responsible for subdomains, whereas GoDaddy has its own DNS server responsible for my second-level domain name.

I have troubles "connecting" provider's DNS server to mine. What records do I need to put into GoDaddy's DNS management console and into my BIND config?

Here are entries at GoDaddy:

A       @               84.23.37.194                            1 h
cname   ftp             @                                       1 h
cname   www             @                                       1 h
cname   _domainconnect  _domainconnect.gd.domaincontrol.com     1 h
ns      @               ns31.domaincontrol.com                  1 h
ns      @               ns32.domaincontrol.com                  1 h

I added one additional entry:

ns  @               ns.xobotun.com                          1 h

Here are my BIND settings:

• file \etc\bind\named.conf.local:

zone "xobotun.com" {
        type master;
        file "/etc/bind/db.xobotun.com";
};

• file \etc\bind\db.xobotun.com:

$TTL    604800
xobotun.com     IN      SOA     ns31.domaincontrol.com. hostmaster.godaddy.com. (
                              2         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL

xobotun.com.    IN      NS      ns31.domaincontrol.com.
xobotun.com.    IN      NS      ns32.domaincontrol.com.
xobotun.com.    IN      A       84.23.37.194

static          IN      A       84.23.37.194
cv              IN      A       84.23.37.194
ns              IN      A       84.23.37.194

I suppose that I should alter the line I added to GoDaddy DNS control panel, but it does not let me enter plain ip address and asks to enter DNS server address in nsXX.nameserver.tld format.

I've been fighting DNS server two days already and gave up. Of course, I can add a string like
A static @ 1h to GoDaddy control panel, but that is way too easy!

EDIT

I ran nmap and found a discrepancy: responding service was not BIND, but pdnsd. That lead me to an answer.

Answer 1

There were several problems:

1. I had previously installed pdnsd as caching DNS server. Even though I have turned it off, it started its daemon every time I was launching service bind9 restart. And yes, it occupied 0.0.0.0 and seemed to respond instead of bind9, however not showing itself in netstat -tulpn. I figured it only after launching nmap from another PC.

2. There was anti-mitm-alike protection on: https://askubuntu.com/questions/768210/bind9-will-not-resolve.

3. Finally and mainly, after several iterations of editing \etc\bind\db.xobotun.com, I accidentally removed point .
xobotun.com IN SOA ns31.domaincontrol.com. hostmaster.godaddy.com. ( It should instead looked like
   xobotun.com. IN SOA ns31.domaincontrol.com. hostmaster.godaddy.com. ( ___________↑

It is working now, thanks!