DHCP can now dynamically update the DNS
server. DHCP updates DNS with the host name and IP address of the
client. For every client DHCP assigns a name and IP address to,
it also adds an address record ("A"), a pointer
record ("PTR"), and a resource record ("RR")
of that client to the DNS server.
To assign a name for every IP address, there is a new tag
known as "pcsn." When this boolean tag is set,
the DHCP server gives priority to the name (if any) provided by
the client. The name should be a fully qualified domain name (FQDN).
If it is not, then the DHCP server will try appending the domain
name (if set using "dn" tag) else it appends "." and updates the
DDNS.
Dynamic DNS Server Update Pre-Requisites |
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The dynamic DNS server has pre-requisites for accepting updates
from the DHCP server. These pre-requisites are used when DHCP server updates
(by either adding or deleting names and IP addresses) the DNS server.
DHCP supports and adheres to the following pre-requisites:
The resource records (RR) should not
exist for an add operation.
The resource records must exist for a delete operation.
You can configure DHCP to ignore these pre-requisites by adding
the "sp" tag to the /etc/dhcptab configuration file.
To enable dynamic updates, you must configure DHCP server
along with the DNS server. See the section “The BIND Configuration File” to
configure the Name Server with the latest options and statements needed
to enable dynamic updates.
HP strongly recommends that DHCP servers and DNS server run
on the same machine for dynamic updates. See Figure 6-2 “DHCP Server and DNS Server running
on HP-UX” for
an illustration of a single HP-UX host running both DHCP and DNS servers.
It shows each server and the daemons for each.
Configuring the DHCP Server to Perform Dynamic Updates |
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Add the tags "pcsn" and "ddns-address," which specifies the address of the
DDNS server, to the dhcp_pool_group or the dhcp_device_group keywords to enable the DHCP server to update the
DDNS. The ddns-address must be the IP address of a local DHCP
server. It cannot be the IP address of a remote system.
DHCP_DEVICE_GROUP:\ ba:\ pcsn:\ class-name=SUBNET_128_XTERMINAL_GROUP:\ class-id="xterminal:"\ subnet-mask=255.255.255.0 :\ addr-pool-start-address= 15.14.128.1 :\ addr-pool-last-address= 15.14.128.254 :\ ddns-address=1.2.3.4:\ lease-time=604800 :\ lease-grace-period=5 :\
