Nat - Draytek Vigor2710 Series User Manual

DNS Server
Configuration
3 . 3 N A T
3 . 3 N A T
Usually, the router serves as an NAT (Network Address Translation) router. NAT is a
mechanism that one or more private IP addresses can be mapped into a single public one.
Public IP address is usually assigned by your ISP, for which you may get charged. Private IP
addresses are recognized only among internal hosts.
When the outgoing packets destined to some public server on the Internet reach the NAT
router, the router will change its source address into the public IP address of the router, select
the available public port, and then forward it. At the same time, the router shall list an entry
in a table to memorize this address/port-mapping relationship. When the public server
response, the incoming traffic, of course, is destined to the router's public IP address and the
router will do the inversion based on its table. Therefore, the internal host can communicate
with external host smoothly.
The benefit of the NAT includes:
of the router, which means the router is the default gateway.
DHCP Server IP Address for Relay Agent - Set the IP address of
the DHCP server you are going to use so the Relay Agent can help
to forward the DHCP request to the DHCP server.
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.
Force DNS manual setting - Force Vigor router to use DNS
servers in this page instead of DNS servers given by the Internet
Access server (PPPoE, PPTP, L2TP or DHCP server).
Primary IP Address -You must specify a DNS server IP address
here because your ISP should provide you with usually more than
one DNS Server. If your ISP does not provide it, the router will
automatically apply default DNS Server IP address: 194.109.6.66
to this field.
Secondary IP Address - You can specify secondary DNS server IP
address here because your ISP often provides you more than one
DNS Server. If your ISP does not provide it, the router will
automatically apply default secondary DNS Server IP address:
194.98.0.1 to this field.
The default DNS Server IP address can be found via Online Status:
If both the Primary IP and Secondary IP Address fields are left
empty, the router will assign its own IP address to local users as a
DNS proxy server and maintain a DNS cache.
If the IP address of a domain name is already in the DNS cache, the
router will resolve the domain name immediately. Otherwise, the
router forwards the DNS query packet to the external DNS server
by establishing a WAN (e.g. DSL/Cable) connection.
30 Vigor2710 Series User's Guide