Sten Carlsen stenc at
Wed Aug 1 11:41:42 UTC 2018

Don’t forget both UDP and TCP port 53 must be open.

Best regards

Sten Carlsen

No improvements come from shouting:


> On 1 Aug 2018, at 13.09, Niall O'Reilly <niall.oreilly at> wrote:
>> On 1 Aug 2018, at 10:01, Mohammed Ejaz wrote:
>> Is there any way to troubleshoot from the master server why there is no synchnization to one more Slave.
> Only partly. You may need access to the slave at some stage.
> Master log should record NOTIFY messages sent to all slaves.
> If not all desired slaves are being sent NOTIFY, master needs to be
> configured with relevant directive (BIND named: also-notify).
> If master is sending NOTIFY, next thing to check is whether slave
> is requesting AXFR/IXFR. Master log should show each transfer.
> If not, then you’ll need to ask sysadmin at slave to check whether
> NOTIFY is arriving and being accepted, and whether slave is actually
> requesting transfer. If not, slave configuration may need
> correction (BIND named: allow-notify).
> If there is still a problem, you’ll likely need to use tcpdump or
> the like to investigate at network level, as NOTIFY or transfer
> may be blocked by a misconfigured firewall or other network fault.
> One other thing: avoid using nslookup. In trying to be “helpful”,
> it hides significant information and makes troubleshooting difficult.
> You’ll save time (yours, and that of anyone who tries to help you)
> by using dig.
> Best regards,
> Niall O’Reilly
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