$TTL 1D
@ IN SOA ns1.test.com. root.test.com. (
  2024090801    ; serial
          1D    ; refresh
          1H    ; retry
          1W    ; expire
     2000000 )  ; minimum

test.com.           3600 IN NS   ns1.test.com.
test.com.           3600 IN NS   ns2.test.com.
ns1.test.com.       3600 IN A    172.18.1.20
ns2.test.com.       3600 IN A    172.18.1.21

www                 3600 IN A    2.3.4.5