3Com 7757 Configuration Manual page 597

n
Configuring DNS
Services for the DHCP
Server
To avoid IP address conflicts, the IP addresses to be dynamically assigned to DHCP
clients are those that are not occupied by specific network devices (such as
gateways and FTP servers).
The lease time can differ with address pools. But that of the IP addresses of the
same address pool are the same. Lease time is not inherited, that is to say, the
lease time of a child address pool is not affected by the configuration of the parent
address pool.
Table 465 Configure to assign IP addresses dynamically
Operation
Enter system view
Create a DHCP address pool
and enter DHCP address pool
view
Set the IP address segment
whose IP addresses are to be
assigned dynamically
Configure the lease time
Return to system view
Specify the IP addresses that
are not dynamically assigned
In the same DHCP global address pool, the network command can be
■
executed repeatedly. In this case, the new configuration overwrites the
previous one.
The dhcp server forbidden-ip command can be executed repeatedly. That is,
■
you can repeatedly configure IP addresses that are not dynamically assigned to
DHCP clients.
If a host accesses the Internet through domain names, DNS is needed to translate
the domain names into the corresponding IP addresses. To enable DHCP clients to
access the Internet through domain names, a DHCP server is required to provide
DNS server addresses while assigning IP addresses to DHCP clients. Currently, you
can configure up to eight DNS server addresses for a DHCP address pool.
You can configure domain names to be used by DHCP clients for address pools.
After you do this, the DHCP server provides the domain names to the DHCP clients
as well while the former assigns IP addresses to the DHCP clients.
Table 466 Configure DNS services for the DHCP server
Operation
Enter system view
Global Address Pool-Based DHCP Server Configuration
Command
system-view
dhcp server ip-pool
pool-name
network ip-address [ mask
mask ]
expired { day day [ hour
hour [ minute minute ] ] |
unlimited }
quit
dhcp server forbidden-ip
low-ip-address
[ high-ip-address ]
Command
system-view
597
Description
-
Required
By default, no DHCP address
pool is created
Required
By default, no IP address
segment is set. That is, no IP
address is available for being
assigned
Optional
The default lease time is one
day
-
Optional
By default, all IP addresses in a
DHCP address pool are
available for being
dynamically assigned
Description
-