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NB1300Plus4 Wireless ADSL Modem Page 101
Appendix D - Frequently Asked Questions
What is DHCP?
DHCP is used to assign IP addresses and other routing information automatically to each
computer on the Network (including Wireless Networks and the Internet). You can manually
assign an IP address on each machine, but this involves having physical access to each machine.
DHCP is a great advantage when dealing with larger networks and for people who do not
nessesarily want to know about IP addresses in order to use their computer.
There are three main things that a DHCP Server (Often a Router or Home Gateway) assigns
each Client computer in the network, these are;
■ IP Address
■ Subnet Mask
■ Default Gateway (Router)
You need an IP address and Subnet Mask correctly assigned to your computer so it can
communicate with other local computers and devices (on the same network). You need the
correct Default Gateway assigned so that your computer knows which device to contact to get
access outside of the local network (e.g. the Internet)
Most ADSL Routers or Gateways have DHCP Servers built into them and they are usually pre-
configured with the most commonly suitable settings. These settings reflect on other default
settings in the Router itself. For example, the Default Gateway IP address which is broadcast to
each client computer is usually the same as the IP address of the router itself. The most
common settings for a DHCP server in NetComm's Routers are as below;
Router's IP address: 192.168.1.1
DHCP Pool Start IP: 192.168.1.100
DHCP Pool End IP: 192.168.1.149
DHCP Subnet mask: 255.255.255.0
Default Gateway IP: 192.168.1.1
Note: Sometimes only the Start IP is given and you specify that the DHCP server should
hand out a certain number of IP addresses (leases).
What is NAT?
NAT (Network Address Translation) is what we rely upon to share our Internet connection
with more than one computer. Because it is not safe or practical to assign every computer in the
world with a Public (Internet) IP address, we cluster computers together and share access to the
Internet via NAT.
NAPT (Network Address Port Translation) takes advantage of the TCP/IP protocol ability to
use many thousands of 'Ports' that exist on each IP address. Instead of using a unique Public IP
address to represent every computer on your internal (Private) network, Dynamic NAPT will
automatically choose a different port on the Public IP address to represent each internal
computer.