Make sure your SOA points to your correct DNS server via nslookup to the two name servers you think may be problematic.
Check the serial number entries (yyyymmddrr) – the largest serial number should also be on the SOA server.
If the highest serial number is on a non-authoritative server, check *that* server’s SOA, correct it.
- set the faulty server’s serial number to something lower than that of the genuine SOA server.
- Lower the faulty server’s Refresh interval to e.g. 600 seconds.
Wait for 10 minutes and make sure the zone on the faulty server matches the zone on the SOA server – especially the serial number.
Raise the now-fixed server’s Refresh interval back to e.g. 86400 seconds.