....... SOA record & lots more stuff .......
 foo.com.      IN        NS        ns1.bar.com.

 foo.com.      IN        A         192.168.100.1
 ....... More A/CNAME/AAAA/etc. records .......

foo.bar.com.     IN NS ns1.foo.bar.com.
ns1.foo.bar.com. IN A  10.10.10.10

foo.bar.com.     IN NS ns1.foo.bar.com.
ns1.foo.bar.com. IN A  10.10.10.10

foo.bar.com.     IN NS ns1.foo.bar.com.
ns1.foo.bar.com. IN A  10.10.10.10

;; ANSWER SECTION:
foo.bar.com.             10800   IN      NS      ns1.foo.bar.com.

;; ADDITIONAL SECTION:
ns1.foo.bar.com.         7972    IN      A       10.10.10.10