There are three nameservers registered in PBAS: NS1, NS2 and NS3. AXFR is sent to NS1 and NS2 immediately, but with delay to NS3.
There are the following messages in /var/log/messages log file of the PBAS server:
Oct 27 12:54:43 hspc01 pdns: AXFR of domain 'example.com' initiated by xx.xx.xx.x1 Oct 27 12:54:43 hspc01 pdns: AXFR of domain 'example.com' initiated by xx.xx.xx.x2 Oct 27 13:27:07 hspc01 pdns: AXFR of domain 'example.com' initiated by xx.xx.xx.x3
Why the third nameserver is updated 30 minutes later?
Hostname of NS3 is not resolvable, but "Use the IP address instead of the hostname for the SSH connection" option is enabled in NS3 properties under
Top > Service Director > Domain Manager > Name Servers > NS3.
Such combination results in a slight delay in transfer to name servers, this is an expected behavior. .
Please make sure that hostname of the troubled server is resolved correctly.