$TTL 24h
@		IN      SOA     mydomain.lan. root.mydomain.lan. (
                         2013011300 ; serial number
                         3h         ; refresh time
                         30m        ; retry time
                         7d         ; expire time
                         3h         ; negative caching ttl
                         )
 
		IN      NS      ns1.mydomain.lan.
		IN      NS      ns2.mydomain.lan.
 
4	IN      PTR     host1.mydomain.lan.