Technical data

Configuring and Managing BIND
5.3 Configuring the BIND Server (BIND 8.1)
The default topology is as follows:
topology { localhost; localnets; };
5.3.3 BIND Configuration Server Statement
Zone transfers can put a heavy load on network traffic and on a BIND server. If
you have a large network with many BIND servers, keeping each server up-to-
date can put a strain on the master server and its memory requirements. You can
use the server statement to control the number of zone transfers that can occur
and the duration of the zone transfer.
The server statement defines characteristics to be associated with a remote name
server. The statement has the following syntax:
server ip_address {
[ bogus yes_or_no; ]
[ transfers number; ]
[ transfer-format ( one-answer | many-answers
);]
[ keys { key_id [key_id ... ] }; ]
};
5.3.3.1 Limiting the Number of Transfers
You can limit the number of zones your name server requests from a single
remote name server by including a transfers substatement on the server
statement. The default limit is two active zone transfers per name server. When
your name server completely receives one of the two zone transfers, if another
request is needed, the request will be sent after waiting a period of time.
Example 5–7 shows how to code the
server statement to limit the number of
transfer requests to name server 16.168.1.2 to three at a time.
Example 5–7 Server Statement
server 16.168.1.2 {
transfers 3
};
5.3.3.2 Efficient Zone Transfers
The BIND 8 transfer-format subcommand specifies how your name server
transfers zone data to its slaves. The server can transfer one resource record in
each DNS message ( one-answer ) or it can transfer as many records as possible
into a single DNS message (
many-answers ). Using the many-answers method
takes less bandwidth to transfer the same amount of data as the one-answer
method and also uses less CPU time to decouple the DNS messages.
Example 5–8 shows how to code the server statement to send more than one
record in the same DNS message to name server 16.168.1.2.
Example 5–8 Server Statement
server 16.168.1.2 {
transfer-format many-answers;
};
5–18 Configuring and Managing BIND