http://markjenkins.ca/reducing-redundancy-in-bind-zone-files/

common_TTL_SOA_NS_CNAME_MX_A_for_cool_zones.db

$INCLUDE "/etc/bind/common_TTL_SOA_NS_CNAME_MX_for_cool_zones.db";
@	A	192.168.1.186

common_TTL_SOA_NS_CNAME_MX_A_for_internal_cool_zones.db

$INCLUDE "/etc/bind/common_TTL_SOA_NS_CNAME_MX_for_cool_zones.db";
@	A	127.0.0.1

common_TTL_SOA_NS_CNAME_MX_for_cool_zones.db

; default TTL
$TTL 3h

; common SOA
@       IN      SOA     cool.tld. domains.cool.tld. (
	2008081401 ; serial, todays date + todays serial
	3H         ; slave refresh frequency
	15M        ; slave retry rate when refresh fails
	4W         ; expire time until slaves give up on refresh
	2D )       ; minimum-TTL if one isn't specified

; common NS
@	NS	cool.tld.

; common CNAME
www	CNAME	@

; common MX
@	MX	10 cool.tld.

cool.tld.db

$INCLUDE "/etc/bind/common_TTL_SOA_NS_CNAME_MX_A_for_cool_zones.db";
$INCLUDE "/etc/bind/cool_extra_sub_domains.db";

cool_extra_sub_domains.db

pics	CNAME	@
chat	CNAME	@

internal_cool.tld.db

$INCLUDE "/etc/bind/common_TTL_SOA_NS_CNAME_MX_A_for_internal_cool_zones.db";
$INCLUDE "/etc/bind/cool_extra_sub_domains.db";

make_zone_list.py

#!/usr/bin/env python

from optparse import OptionParser
from sys import stdout

option_parser = OptionParser()
option_parser.add_option("-p", "--prefix", default="")
option_parser.add_option("-s", "--suffix", default="")
(options, args) = option_parser.parse_args()

def iterjoin(join_str, iterable):
    first = True
    for value in iterable:
        if not first:
            yield join_str
        else:
            first = False
        yield value

if len(args) > 0:
    input_file = file(args[0])
    stdout.writelines( 
        iterjoin("\n", 
        ("""zone "%(zone_name)s" {
\tfile "%(file_prefix)s%(zone_name)s%(file_suffix)s";
\ttype master;
};
""" % {'zone_name': line.strip(), 
       'file_prefix': options.prefix,
       'file_suffix': options.suffix, }
         for line in input_file 
         if len(line.strip()) > 0 ) ) )
    input_file.close()
else:
    exit(1)

Makefile

# Makefile
ZONE_LIST=zone_list_file
ZONE_FILE_SUFFIX=".db"

all: zone_list.zones internal_zone_list.zones

zone_list.zones: $(ZONE_LIST) Makefile
	./make_zone_list --prefix "/etc/bind/" \
	--suffix $(ZONE_FILE_SUFFIX) $^ > $@

internal_zone_list.zones: $(ZONE_LIST) Makefile
	./make_zone_list --prefix "/etc/bind/internal_" \
        --suffix $(ZONE_FILE_SUFFIX) $^ > $@

named.conf

// this is named.conf, it implements split DNS
include "/etc/bind/named.conf.options";

view "local_network"
{
	match-clients {localhost; };
	recursion yes;

	// prime the server with knowledge of the root servers
	zone "." {
		type hint;
		file "/etc/bind/db.root";
	};

	// Consider adding the 1918 zones here, if they are not used in your
	// organization
	include "/etc/bind/zones.rfc1918";

	// be authoritative for the localhost forward and reverse zones, and for
	// broadcast zones as per RFC 1912

	zone "localhost" {
		type master;
		file "/etc/bind/db.local";
	};

	zone "127.in-addr.arpa" {
		type master;
		file "/etc/bind/db.127";
	};

	zone "0.in-addr.arpa" {
		type master;
		file "/etc/bind/db.0";
	};

	zone "255.in-addr.arpa" {
		type master;
		file "/etc/bind/db.255";
	};

	include "/etc/bind/internal_zone_list.zones";
};

view "external_network"
{
	match-clients {!localhost; any; };
	recursion no;

	// prime the server with knowledge of the root servers
	zone "." {
		type hint;
		file "/etc/bind/db.root";
	};

	include "/etc/bind/zone_list.zones";
};

zone_list.zones

zone "cool.tld" {
	file "/etc/bind/cool.tld.db";
	type master;
};

zone_list_file

cool.tld
super.tld