Chaining NOTIFY and slave servers - is it supported?

[Anand Buddhdev]

On 21/04/2020 17:05, Petr Bena wrote:

Hi Petr,

> So when someone changes zone on A via nsupdate, NOTIFY and subsequent
> IXFR goes like this: A -> B -> C instead of:

This is just fine. There are many DNs setups organised like this. Your
configuration isn't unique or strange.

> What confuses me however, is that I just found this in BIND
> documentation at:
> https://www.zytrax.com/books/dns/ch7/xfer.html#also-notify
> 
> "The *also-notify* statement is relevant only with master zones..."
> 
> If also-notify works only with master zones, then why this works? Is it
> even supposed to work? Is this a supported configuration at all?

The terms "master" and "slave" are relative, and bear no relation to how
a server loads a zone (from a file, XFR, database, etc). Any server that
provides XFR to another is a master, and the receiver of such an XFR is
a slave.

In your case, the "B" server is both a slave (of A), and a master (to
C). Nothing wrong with this.

Regards,
Anand