I installed ISPConfig on Debian Jessie host and made it as a third name server for a multiserver setup. I set it as mirror of ns1. Now the changes I made do get to ns3, but it does not get the full pri. -file. I have tried stuff, but no luck. The Resync Tool does not offer ns3 or ns2 as alternatives, so that does not help. I read in previous post about copying all the pri files manually, but do I have to do that each time I add this third ns to a zone? To show the problem, here pri files from ns2 and ns3. Code: root@ns2:/etc/bind# cat pri.design.yt $TTL 86400 @ IN SOA ns1.ZZZZZZZZZZ.fi. hostmaster.ZZZZZZZZZZ.fi. ( 2017052403 ; serial, todays date + todays serial # 28800 ; refresh, seconds 7200 ; retry, seconds 604800 ; expire, seconds 86400 ) ; minimum, seconds ; design.yt. 86400 A 22.214.171.124 foo.design.yt 3600 A 126.96.36.199 ftp.design.yt. 86400 CNAME design.yt. www.design.yt. 86400 CNAME design.yt. design.yt. 86400 MX 10 posti.ZZZZZZZZZZ.fi. design.yt. 86400 NS ns1.ZZZZZZZZZZ.fi. design.yt. 86400 NS ns2.ZZZZZZZZZZ.fi. design.yt. 86400 NS ns3.ZZZZZZZZZZ.fi. design.yt. 86400 TXT "v=spf1 mx ~all" Code: root@ns3:/etc/bind# cat pri.design.yt $TTL 86400 @ IN SOA ns1.ZZZZZZZZZZ.fi. hostmaster.ZZZZZZZZZZ.fi. ( 2017052403 ; serial, todays date + todays serial # 28800 ; refresh, seconds 7200 ; retry, seconds 604800 ; expire, seconds 86400 ) ; minimum, seconds ; foo.design.yt 3600 A 188.8.131.52 design.yt. 86400 NS ns3.ZZZZZZZZZZ.fi. So ns3 does get the SOA record with correct serial number, but not the lines that were there before I installed ns3. If I understood the ISPConfig Manual correctly, I could also add secondary DNS, which looks like then ns3 would be a slave server in BIND9 sense. That I would know how to force to a zone transfer. And this mirror of ns1 and slave can not be used at the same time, I have to choose one way or another. Since ns2 already is mirror of ns1, it seemed easier to make ns3 same way so I do not get two different setups. I also realised only when debugging this that ns2 is master of the zone, I assumed it would be a slave. I have previously only used bind and set up master and slaves manually. It looks to me this mirroring of ns1 makes it so that ns2 and ns3 do not do bind9 zone transfers at all, there is some ISPConfig magic that syncs the pri files.