Change your authoritative DNS Serial

dns-inc-zone-serial.py

#!/usr/bin/env python
import os
import re
import time

file = "<put/your/db.domain.tld/zone/file/here>"
date = time.strftime("%Y%m%d")
regex = r"^( *)(20[0-9]{6})([0-9]{2}) ; Serial"
new_date = ""
with open(file) as fp:
    with open(file+'.tmp','w') as dest:
        for line in fp.readlines():
            if re.match(regex, line):
                #print "match"
                rgx = re.match(regex, line)
                nb_spaces = rgx.group(1)
                last_date = rgx.group(2)
                last_serial = rgx.group(3)
                if last_date != date:
                    new_date = date
                    serial="01"
                else:
                    new_date = last_date
                    serial = int(last_serial) + 1
                    if serial < 10:
                        serial = "%02d" % (serial,)
                print nb_spaces + new_date + serial + ' ; Serial'
                dest.write(nb_spaces + new_date + serial + ' ; Serial'+'\n')
            else:
                #pass
                print line.strip('\n')
                dest.write(line)
print "$ diff <put/your/db.domain.tld/zone/file/here>{,.tmp}"

Your file dns-db-zone, should look like :

$ORIGIN domain.tld.
$TTL 7200

; SOA

@       IN      SOA    ns1.domain.tld. hostmaster.domain.tld. (
                                        2016110103 ; Serial
                                        7200       ; Refresh
                                        1800       ; Retry
                                        1209600    ; Expire
                                        86400 )    ; Minimum

; NAMESERVERS
@    IN    NS    ns1.domain.tld.

; A RECORDS
@            IN    A    xx.xxx.xxx.xx
nethost      IN    A    xx.xxx.xxx.xx
ns1          IN    A    xx.xxx.xxx.xx
home         IN    A    xx.xxx.xxx.xx
[...]

; CNAME RECORDS
www         IN    CNAME    nethost
jabber      IN    CNAME    nethost
[...]

for bind9/nsd