DNS configuration on virtual machine without internet - configuration

Question

Im trying to configure DNS server on my virtual computer without internet connection.
I'm using PowerDNS with BIND backend.
Here is my configuration of zone:
$ORIGIN example.com.
$TTL 86400
# IN SOA example2.com. (
2017020401 ; serial
3600 ; refresh
1800 ; retry
604800 ; expire
86400 ) ; minimum TTL
example.com. 172800 IN NS example1.com.
example.com. 172800 IN NS example2.com.
example.com. 172800 IN NS example3.com.
Im testing server with command dig, which looks like this :
root#osboxes:~# dig example.com #127.0.0.1 -p 5301
; <<>> DiG 9.16.1-Ubuntu <<>> example.com #127.0.0.1 -p 5301
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13819
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;example.com. IN A
;; AUTHORITY SECTION:
example.com. 3600 IN SOA example2.com. 2017020401.example.com. 3600 1800 604800 86400 3600
;; Query time: 180 msec
;; SERVER: 127.0.0.1#5301(127.0.0.1)
;; WHEN: Wed Feb 03 16:45:50 EST 2021
;; MSG SIZE rcvd: 96
I want the request to be delegated to other servers example1.com, example2.com and example3.com.
For that, I need to have my NS records in AUTHORITY SECTION of the dig output.
However, its not happening, there is only the SOA record.
I tried to remove the SOA record, but afterwards I have no record in AUTHORITY SECTION.
Can somebody help me solving this problem please? What am I missing?
EDIT : adding configuration
recursor.conf
local-address=0.0.0.0
local-port=5301
allow-from=127.0.0.0/8, 10.0.0.0/8
forward-zones=example.com=127.0.0.1:5300
pdns.conf
launch=bind
bind-config=/etc/powerdns/named.conf
local-address=127.0.0.1
local-port=5300
named.conf
zone "example.com" IN {
type slave; # type of zone
file "/var/lib/powerdns/zone.net"; # location of forward zone file
allow-query { any; };
};
/var/lib/powerdns/zone.net
$ORIGIN example.com.
$TTL 86400
# IN SOA example2.com. (
2017020401 ; serial
3600 ; refresh
1800 ; retry
604800 ; expire
86400 ) ; minimum TTL
example.com. 172800 IN NS example1.com.
example.com. 172800 IN NS example2.com.
example.com. 172800 IN NS example3.com.

Answer 1

EDIT
I'm assuming you're using BIND9. If you are, you need to set minimal-responses to no in your options section. Most likely that's in /etc/bind/named.conf.options, if it's not there, then check /etc/bind/named.conf.
I found this on readthedocs for BIND, scroll down a bit and you'll see minimal-responses highlighted.
END EDIT
The dig query you tried is for example.com type A, which is an IPv4 address. Your zone file doesn't have any A records for example.com, so one thing you could do is add one, for example:
example.com. 172800 IN A 1.2.3.4
Then your dig query for example.com should return 1.2.3.4 in the answer section, and the NS records in the authority section (though that may depend on your DNS server's configuration).
If you add A (or AAAA) records for example1.com, example 2.com, and example3.com and then do your dig command again, you'll probably get those A records in the additional section. (IIRC, that's known as "glue")
Just a little more background, the response you got from your dig query is often called a "No Data" response. That means there's a record for the name you looked up (example.com), but it's a different type (NS) than the one you asked for (A), so it returns a NOERROR rcode with no answer (there's no answer section). If you ask for a name that doesn't exist at all, you'll get the same thing (no answer section), but an NXDOMAIN rcode instead of NOERROR.