Draytek Vigor2920 Series User Manual page 163

Item
DNS Server IP Address
Description
can manually assign IP address to every host in the LAN.
Enable Relay Agent –Specify which subnet that DHCP server
is located the relay agent should redirect the DHCP request to.
Start IP Address - Type a value of the IP address pool for the
DHCP server to start with when issuing IP addresses. If the 1st
IP address of your router is 192.168.1.1, the starting IP address
must be 192.168.1.2 or greater, but smaller than 192.168.1.254.
IP Pool Counts - Type the maximum number of PCs that you
want the DHCP server to assign IP addresses to. The default is
50 and the maximum is 253.
Gateway IP Address - Type a value of the gateway IP address
for this subnet. The value is usually as same as the 1st IP
address of the router, which means the router is the default
gateway.
Lease Time – Type the time to determine how long the IP
address assigned by DHCP server can be used.
Retrieve IPs from inactive clients periodically – Whenever a
DHCP client requests an IP address from the LAN DHCP
server, the server will give out an IP to this client for a certain
amount of time (e.g., 1 day). However, even if this client only
uses the IP for say 5 minutes, the server still "reserves" 1 day
for that client. Because a DHCP server only has a limited
number of IPs to lease to its DHCP clients, soon enough all the
IPs will be used out and then no one will be able to get any IPs
from this server anymore. Therefore, this feature is used to get
the IP back from inactive clients (i.e. doesn't use the IP but the
server still reserves the IP for him).
DNS stands for Domain Name System. Every Internet host
must have a unique IP address, also they may have a
human-friendly, easy to remember name such as
www.yahoo.com. The DNS server converts the user-friendly
name into its equivalent IP address.
Primary IP Address - You can specify the primary DNS
server IP address here. The Router will assign the specified
DNS server IP instead of the ISP offered DNS server IP to
LAN DHCP clients.
Secondary IP Address - You can specify the secondary DNS
server IP address here. Router will assign the specified DNS
server IP instead of the ISP offered DNS server IP to LAN
DHCP clients.
The default DNS Server IP address can be found via Online
Status:
If both DNS Primary IP and Secondary IP Address fields are
left empty, the router will assign the DNS server IP obtained
from ISP (which can be found in Online Status page) to LAN
DHCP clients.
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Vigor2920 Series User's Guide