diff --git a/dns_sync.py b/dns_sync.py
index 0902255..204650d 100755
--- a/dns_sync.py
+++ b/dns_sync.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 # coding: utf-8
 
-import datetime
+import datetime, os, commands, sys, shutil
 from django.core.management import setup_environ
 #from dns_mdb import settings
 import settings
@@ -10,9 +10,109 @@ setup_environ(settings)
 
 from mdb.models import *
 
-domains = Domain.objects.all()
 
+to_be_updated = []
 zones = {}
+zone_file_temp_dir = "temp"
+zone_file_dir = "/var/lib/bind"
+zone_command = "/usr/sbin/named-checkzone %s %s"
 
+if not os.path.isdir(zone_file_temp_dir):
+	os.mkdir(zone_file_temp_dir)
+
+
+class Log():
+	filename = None
+	started = False
+
+	def startlog(self):
+		if self.started:
+			return
+		logfile = open(self.filename, "a")
+		logfile.write("\nStarting log %s\n" % str(datetime.datetime.now()))
+		logfile.close()
+		self.started = True
+
+	def setFilename(self, filename):
+		self.filename = filename
+	
+	def debug(self, string):
+		self.startlog()
+		logfile = open(self.filename, "a")
+		logfile.write("%s\n" % string)
+		logfile.close()
+		print string
+
+log = Log()
+log.setFilename("dns_sync.log")
+
+def valid_zone(zone, filename):
+	status, output = commands.getstatusoutput(zone_command % (zone, filename))
+	if status != 0:
+		print "Could not validate zone:\n%s" % output
+		return False
+	else:
+		return True
+
+
+# this will produce the zone files for the domains
+domains = Domain.objects.all()
 for domain in domains:
-	print domain.zone_file_contents()
+	current_serial = 0
+	if os.path.exists("%s/%s" % (zone_file_dir, domain.domain_filename)):
+		zonefile = open("%s/%s" % (zone_file_dir,domain.domain_filename), "r")
+		firstline = zonefile.readline()
+		current_serial = int( firstline.split(":")[1])
+		
+		zonefile.close()
+	
+	if current_serial < domain.domain_serial:
+		log.debug("Updating zone %s from %d -> %d" %
+			(domain.domain_name, current_serial, domain.domain_serial))
+		zone_contents = domain.zone_file_contents()
+		zonefile = open("%s/%s" % (zone_file_temp_dir, domain.domain_filename),"w")
+		zonefile.write(zone_contents)
+		zonefile.close()
+		if valid_zone(domain.domain_name, "%s/%s" %
+				(zone_file_temp_dir, domain.domain_filename)):
+			to_be_updated.append( [ domain.domain_name, "%s/%s" %
+				(zone_file_temp_dir, domain.domain_filename) ] )
+
+# this will produce the zone files for the reverse lookup subnets
+subnets = Ip4Subnet.objects.all()
+for domain in subnets:
+	current_serial = 0
+	if os.path.exists("%s/%s" % (zone_file_dir, domain.domain_filename)):
+		zonefile = open("%s/%s" % (zone_file_dir,domain.domain_filename), "r")
+		firstline = zonefile.readline()
+		current_serial = int( firstline.split(":")[1])
+		
+		zonefile.close()
+	
+	if current_serial < domain.domain_serial:
+		log.debug("Updating zone %s from %d -> %d" %
+			(domain.domain_name, current_serial, domain.domain_serial))
+		zone_contents = domain.zone_file_contents()
+		zonefile = open("%s/%s" % (zone_file_temp_dir, domain.domain_filename),"w")
+		zonefile.write(zone_contents)
+		zonefile.close()
+		if valid_zone(domain.domain_name, "%s/%s" %
+				(zone_file_temp_dir, domain.domain_filename)):
+			to_be_updated.append( [ domain.domain_name, "%s/%s" %
+				(zone_file_temp_dir, domain.domain_filename) ] )
+
+if len(to_be_updated) == 0:
+	# nothing to do
+	sys.exit(0)
+
+for upd in to_be_updated:
+	shutil.copy(upd[1], zone_file_dir)
+
+status, output = commands.getstatusoutput("/etc/init.d/bind9 reload")
+
+if status != 0:
+	print output
+	sys.exit(1)
+
+sys.exit(0)
+