Unless you delete the file and restart (which is what you're doing). Serial number value should be updated whenever do changes on the zone file.
I didn't change the serial number in the zone file.
Some of the information in this article is advanced material we make available as a courtesy.
Please be advised that you are responsible for properly following the procedures below. We strongly encourage you to keep the DNS service BIND (Berkeley Internet Name Domain) updated with the latest version on your Dedicated Server.
To verify that the domain and forest partition as well as the # ls -lai /usr/local/samba/private/d/ 17344368 -rw-rw---- 2 root named 4251648 11.
If BIND uses incorrect Kerberos settings on the Samba Active Directory (AD) domain controller (DC), dynamic DNS updates fail.
that's the reason, why it's not updated in slave server.
Theoretically: Serial numbers in DNS zone files provide a way for the server to verify that the contents of a particular zone file are up-to-date.
Adding this line to the configuration file will prevent yum from ever being able to update these packages.
This can cause issues in the future should you want to use yum to update anything listed as an exclude.