Toshiba E-STUDIO850 - Setting up DNS and Mail Servers

2. Setting up Network Server
76 Network Administration Guide — Setting up DNS and Mail Servers
Setting up DNS and Mail Servers
This section describes how to set up the DNS server and Mail server for the Internet
connection.
The figure illustrates a general network environment for Internet connection from a local
area network.
As shown in the figure above, a local area network usually consists of several seg-
ments: one connects to the router directly (and is assigned a Global IP address) and
others are for client computers.
To enable Internet access from the local area network, the router must be assigned a
Global IP Address. In the above figure, the Private IP addresses have been assigned
to all devices in the local area network, and the router maps between the Private IP
addresses and Global IP Addresses using the NAT, Network Address Translation. This
gives clients and servers access to the Internet through the router.
Regarding the security, it is preferred to place this equipment in a different segment
from the router that connects to the Internet.
Also, in order to enable Internet communication from the device in the local area net-
work, the Domain Name Service is used. In the Internet, the DNS server specifies the
domain name related to the global IP address of the servers. To recognize the domain
names in the Internet, the domain names must be registered in both the DNS server in
the Internet, which is managed by the public DNS organization, and the DNS server in
the local area network where the remote devices are actually located. To configure the
DNS server in your local area network, create following records in the DNS server:
• DNS zone name (i.e. “ifax.com”)
• Host name of the DNS server (i.e. “nshost”)
Client Client
DNS Server Email Server
Router
Internet
LAN
192.168.0.2 192.168.0.3
Proxy Server
192.168.0.3
192.168.0.4
192.168.1.1
192.168.1.2 192.168.1.3 192.168.1.4
192.168.0.1
Global IP Address
Router