DNS Configuration and Management Manual (G06.27+, H06.05+, J06.03+)

BIND 9.x on the NonStop Server
HP DNS Configuration and Management Manual—529432-003
2-5
Dynamic Update
For dynamic updates to be processed by the name server, you must specify the IP
addresses of the systems from where the requests can be received in the configuration
file under the zone entry.
You can enable dynamic update on a zone-by-zone basis by including an
allow-update or update-policy clause in the zone statement. The basic syntax
of such an entry in the configuration file is:
All changes made to a zone using dynamic update are stored in the zone’s journal file.
This file is automatically created by the server when the first dynamic update takes
place. To form the name of the journal file, append the extension.jnl to the name of
the corresponding zone file. The journal file is in a binary format; do not edit this file
manually.
Key Aspects of the Dynamic Update Process
•
The client queries its configured name server to find the authoritative name server
for the domain name it is attempting to update.
•
The local name server for the client performs the standard name-resolution
process to discover the authoritative name server.
•
The client sends a dynamic update request to the authoritative name server for the
zone that the client is attempting to update.
•
The dynamic update request of the client may include a list of prerequisites that
must be fulfilled before an update can be made.
•
During processing, the name server changes the zone and increments the serial
number (resource record parameter) to signal the change to the zone’s slave
server.
•
Slave servers get a new copy of the zone through zone transfers or Incremental
Zone Transfers.
The List of Prerequisites
When an authoritative DNS server receives a dynamic update request, it checks
whether prerequisites have been fulfilled. If the prerequisites are fulfilled, it performs
the requested update. In our example, the DNS server’s client is the DHCP server. The
Note. In this manual, configuration file and named.conf file are used interchangeably.
zone "zone-name" {
type master;
file "zone filename";
allow-update { list of IP-addresses; };
};
Note. The client is the host initiating the dynamic update; in the DHCP example that follows,
the client is the DHCP server.