Serial numbers in zone files: Yours and nameds [Video]

Serial numbers in zone files help your DNS service determine whether it should re-ingest your zone files or ignore them. But there’s more to these pseudo timestamps than meets the eye. In fact, the number that you put in your file and the one that DNS extracts from it might be as different as 200907270001 and 3338774385.

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. If the serial number in a zone file hasn’t changed since that zone was last loaded, named figures that it can ignore the file. This means that sysadmins have to remember to update the serial number every time they make a change to a zone file — otherwise, their changes won’t be picked up and published.

The format of the serial number is fairly flexible. Some sysadmins like to …