$ORIGIN example.com.
$TTL 3600

@	IN	SOA	dns1.example.com. hostmaster.example.com. (
		2010111217	; serial
		6h		; refresh
		1h		; retry
		1w		; expire
		1d )		; minimum

	NS	ns2.d

d	NS	ns1.d
ns1.d	A	1.2.3.4

; glue below another delegation is not mandatory