# SOA and NS record
$SOA 1800 rbl.example.com abuse.example.com 0 600 600 86400 600

# note: NS record should have reasonably longer TTL
$NS  86400 rbl.example.com

# default value if LHS of key is omitted:
:127.0.0.2:spam received, see http://rbl.example.com/lookup?$

# a key without value: returns the default value above
127.0.0.1

# CIDR notation:
10.200/16

# without netmask, it works as well: same as 10.201/16
10.201

# whitelisting:
!10.202.0.1

# domain-based DNSBL:
evil.example.com