Installing and Administering Internet Services

Chapter 3 75
Configuring and Administering the BIND Name Service
Overview of the BIND Name Service
Figure 3-1 Structure of the DNS Name Space
DNS Change Notification
Starting with BIND 8.1.2, DNS notification, also known as DNS notify is
supported. This allows master servers to inform slaves that new
information is ready. The original DNS protocol required slave servers
(secondaries) to poll a master at an interval defined in the Start of
Authority (SOA) record. At these defined intervals, the slave checked the
SOA record on the master to see whether the serial number had
changed. If a change was detected, the slave initiated a zone transfer.
The disadvantage of this approach is that slaves might not get new
information in a timely fashion.
DNS notify provides a way for a master to notify servers that a zone
transfer is necessary. The DNS notify operating users a new DNS opcode.
Currently, DNS Notify can be used only when a zone’s SOA record
changes. The notification is sent to every host listed as a name server in
nameserver records for the zone. In addition BIND 8.1.2 lets you list
additional servers to accommodate stealth servers that may not be listed
in any name server records. You can use the zone statement to list these
additional servers in the configuration file, /etc/named.conf.
When a slave server receives the notify packet, it sends an
acknowledgment. It then behaves as if its refresh timer for that zone has
expired, going through the same process used at expiration time - first
retrieving the SOA record from the master, then initiating a zone
transfer if the record has changed.
. (root)
com edu
inc nmt
purdue
cs
econdiv
indigo arthur
venus
= host
= domain