[Pdns-users] PDNS Server migration - Using AXFR to a Slave-Capable Backend

[Mislav | SysAdmin]

Hi. I've the following setup:
1) pdns server version 3.1 - with mysql backend
2) pdns server version 4.1.0 - with mysql backend

What I'm trying to do is:
- replace version 3.1 with 4.1.0 and I've installed clean version of 
4.1.0 to a new server and I'm trying to this this now:
https://doc.powerdns.com/authoritative/migration.html#using-axfr-to-a-slave-capable-backend

Although this is working fine, my zones are transfered, AXFR is working, 
I've a small problem/question related to that.
Every time I add some domain, I always get 2-3 empty records, here is 
the zone example:
1) https://pastebin.com/LpnzKjwW - this is original master zone from 3.1.
2) https://pastebin.com/5uV2Lk5N - slave zone added on 4.1.0 and 
transfered using AXFR

You will see that first zone has 23 records and when transferred, it has 
25 records. Any idea why is there always something in
the name, but type and content are always empty? It doesn't matter if 
master is pdns server 3.1, I've also tested it with one
bind/named master server and in that scenario result was the same. 
Always 2-3 empty records in the zone. How to debug
this in order to find out why are those getting created in the first 
place? Or how to fix this?