Technical data

Configuring the DHCP Client
8.2 DHCP Client Components
Table 8–2 Supported Request Parameters
Parameter Name
DHCP Option
Code This parameter requests...
Interface-specific parameters
broadcast_address 28 The broadcast address in use on the client’s
subnet.
interface_mtu 26 The MTU size to use when performing Path
MTU discovery.
subnet_mask 1 The client’s subnet mask.
Systemwide parameters
dns_domain_name 15 The domain name that the client should
use when resolving host names using the
Domain Name System (DNS).
dns_servers 6 A list of DNS name servers available to the
client.
host_name 12 The host name of the client.
ip_time_to_live 23 The default time-to-live value the client
should use on outgoing datagrams.
ip_forwarding 19 How the client should configure its IP layer
for packet forwarding.
keepalive_interval 38 The time interval (in seconds) that the
client TCP should wait before sending a
keepalive message on a TCP connection.
routers 3 A list of IP addresses for routers on the
client’s subnet. Routers are listed in the
order of preference.
static_routes 33 A list of static routes the client should
install in its routing cache. If multiple
routes to the same destination are specified,
they are listed in descending order of
priority. The routes consist of a list of IP
address pairs. The first address is the
destination address and the second address
is the router for the destination.
tcp_default_time_to_live 37 The default time-to-live value that the
client uses when sending TCP segments.
8.2.2.2 The Interface File
When the DHCP client receives parameters to configure the interface on the
client, it stores them in a file named ifname.DHC along with the IP address lease
information. The ifname part of the file name is the name of the interface on
which the parameters were received. For example, the file created for parameters
received on interface SE0 is SE0.DHC. There is one file per interface, and the files
are placed in the directory specified by the system logical name TCPIP$DHCP_
CONFIG (if it is defined) or in the SYS$SYSDEVICE:[TCPIP$DHCP] directory.
The interface file is a binary file, and you can display its contents by using the
SHOWDHC utility. See Section 8.6 for information on how to use the SHOWDHC
utility.
Configuring the DHCP Client 8–9