If the soa table contains a column named xfer and DNS-based
zone transfers are enabled See Zone transfers, the xfer column
will be examined whenever a DNS-based zone transfer request is received.
The xfer column should contain one or more IP addresses separated
by commas. These IP addresses will be allowed to transfer the zone. If
the xfer column is empty, no DNS-based zone transfers will be allowed
for that zone. The IP addresses may contain standard wildcard characters.
Thus, if you want to grant zone transfer access for a particular zone to any
IP address, you would set xfer=*.
The xfer column may be any size you want, and whatever size you think
will be adequate for the IP address lists you intend to use.
To create an xfer column on your soa table, for example, you
might issue SQL statements like this:
mysql> ALTER TABLE mydns.soa ADD COLUMN xfer CHAR(30) NOT NULL;
Query OK, 66380 rows affected (1.82 sec)
Records: 66380 Duplicates: 0 Warnings: 0