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
2-6
Dynamic Update
DHCP server must have dynamic update capability; however, the DHCP server and
the DNS server need not reside on the same subnetwork.
The prerequisites may be of the type:
•
The resource record set exists
•
The resource record set does not exist
•
The name is in use
•
The name is not in use
Tracking the Update Versions
One of the parameters of the Start of Authority (SOA) resource record is the serial
number, which identifies the version of the zone information. Once an update is done,
the master server increments the serial number and sends out a Notify announcement
with the serial number to the zone’s slaves. This Notify message is sent only to the set
of machines whose IP addresses have been specified in the also-notify option
statement in the configuration file.
The secondary servers now get a copy of the updated zone file through zone transfers
or Incremental Zone Transfers.
You can configure slave servers to forward any dynamic updates to their zone data to
the master server for the zone by adding the allow-update-forwarding option to
the slave zone statement in the named.conf file. The allow-update-forwarding
option takes an ACL as its parameter. (See Use ACLs on page 3-9.)
Note. It is very important that secret slave servers, which the master server is unaware of, are
listed in the also-notify zone option in the master server’s named.conf file. This
arrangement is only necessary if you have secret slaves for which NS records are not kept in
the master server's zone data file because no other mechanism exists through which the
master server would know who its secret slave servers are.
Note. You can use the allow-update option to specify which hosts are allowed to submit
dynamic DNS updates for master zones. By default, updates from all hosts are denied. The
allow-update option is not applicable for slave zones.
Example 2-1. Zone File With allow-update
zone "example.com " {
type master;
file "db.example";
allow-update { 10.53.0.24; };
};