inside the mind of a linux admin

DNS Zones and Serial Numbers 101

Recently, there’s been a few instances I’ve come across where DNS updates have been “stuck” or broken due to people screwing up the zone serial numbers. The fields of the zone’s SOA resource record, in particular the “serial number”, determines whether an actual data transfer need occur at all.

The name servers compare the serial number of the SOA resource record on the clusters with the serial number in the last copy of that resource record that it has. If the serial number of the record being transferred is greater (numerically), the data in the zone are deemed to have “changed” (in some fashion) and the name servers proceeds to request the actual zone data transfer from the clusters and propagates the update.

The format in which I use (and 99% of the internet as well) is based on the following format: YYYYMMDDnn

YYYY = year
MM = month
DD = day
nn = revision number

For sanity purposes, this helps us better determine when the last change was made, but more importantly tells the name servers to pull the changes made from the respective name server. If you are unsure of the format, please ask a senior admin or simply increase the last digit in the revision number incrementally by one.

Related Posts

How to revert back to X11 / Xorg from Wayland

Wayland is intended as a “simpler replacement for X”, and is getting quite a bit of hype around the Linux community. So much so, that it’s the default in the latest versions of Fedora, GNOME, KDE and others. While Wayland may be the future, it really is in future. At least for Ubuntu 17.10. The […]

Read More

Touchpad stops working after sleep + resume (Fedora 26 on Dell XPS)

After recently upgrading my Dell XPS 13 w/Touchscreen to Fedora 26, the touchpad suddenly stopped working upon resuming from sleep mode. It was reproduced 100% of the time, and required a complete restart in order to get the touchpad working again. There have been several forum posts and bug reports regarding others experiencing these exact […]

Read More

Twitter: kireguy

Tweeter button Facebook button Myspace button