Bind 9 Administrator Reference Manual

Chapter 6. BIND 9 Configuration Reference
serial-query-rate
Slave servers will periodically query master servers to find out if zone serial numbers have changed.
Each such query uses a minute amount of the slave server’s network bandwidth. To limit the amount
of bandwidth used, BIND 9 limits the rate at which queries are sent. The value of the
serial-query-rate option, an integer, is the maximum number of queries sent per second. The
default is 20.
serial-queries
In BIND 8, the serial-queries option set the maximum number of concurrent serial number queries
allowed to be outstanding at any given time. BIND 9 does not limit the number of outstanding serial
queries and ignores the serial-queries option. Instead, it limits the rate at which the queries are sent
as defined using the serial-query-rate option.
transfer-format
Zone transfers can be sent using two different formats, one-answer and many-answers. The
transfer-format option is used on the master server to determine which format it sends.
one-answer uses one DNS message per resource record transferred. many-answers packs as many
resource records as possible into a message. many-answers is more efficient, but is only supported
by relatively new slave servers, such as BIND 9, BIND 8.x and patched versions of BIND 4.9.5.
The default is many-answers. transfer-format may be overridden on a per-server basis by using
the server statement.
transfers-in
The maximum number of inbound zone transfers that can be running concurrently. The default
value is 10. Increasing transfers-in may speed up the convergence of slave zones, but it also may
increase the load on the local system.
transfers-out
The maximum number of outbound zone transfers that can be running concurrently. Zone transfer
requests in excess of the limit will be refused. The default value is 10.
transfers-per-ns
The maximum number of inbound zone transfers that can be concurrently transferring from a given
remote nameserver. The default value is 2. Increasing transfers-per-ns may speed up the
convergence of slave zones, but it also may increase the load on the remote nameserver.
transfers-per-ns may be overridden on a per-server basis by using the transfers phrase of the
server statement.
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