Netgear Cable/DSL ProSafe Firewall FR328S User Manual download pdf (Page 106)

FR328S ProSafe Firewall with Dial Back-Up Reference Manual v2

B-10 Networks, Routing, and Firewall Basics

M-10207-01, Reference Manual v2

Domain Name Server

Many of the resources on the Internet can be addressed by simple descriptive names such as

www.NETGEAR.com. This addressing is very helpful at the application level, but the descriptive

name must be translated to an IP address in order for a user to actually contact the resource. Just as

a telephone directory maps names to phone numbers, or as an ARP table maps IP addresses to

MAC addresses, a domain name system (DNS) server maps descriptive names of network

resources to IP addresses.

When a PC accesses a resource by its descriptive name, it first contacts a DNS server to obtain the

IP address of the resource. The PC sends the desired message using the IP address. Many large

organizations, such as ISPs, maintain their own DNS servers and allow their customers to use the

servers to look up addresses.

IP Configuration by DHCP

When an IP-based local area network is installed, each PC must be configured with an IP address.

If the PCs need to access the Internet, they should also be configured with a gateway address and

one or more DNS server addresses. As an alternative to manual configuration, there is a method by

which each PC on the network can automatically obtain this configuration information. A device

on the network may act as a Dynamic Host Configuration Protocol (DHCP) server. The DHCP

server stores a list or pool of IP addresses, along with other information (such as gateway and DNS

addresses) that it may assign to the other devices on the network. The FR328S Firewall has the

capacity to act as a DHCP server.

The FR328S Firewall also functions as a DHCP client when connecting to the ISP. The firewall

can automatically obtain an IP address, subnet mask, DNS server addresses, and a gateway address

if the ISP provides this information by DHCP.

Internet Security and Firewalls

When your LAN connects to the Internet through a router, an opportunity is created for outsiders

to access or disrupt your network. A NAT router provides some protection because by the very

nature of the process, the network behind the router is shielded from access by outsiders on the

Internet. However, there are methods by which a determined hacker can possibly obtain

information about your network or at the least can disrupt your Internet access. A greater degree of

protection is provided by a firewall router.

1 2 ... 101 102 103 104 105 106 107 108 109 110 111 ... 134 135

No comments

Netgear Cable/DSL ProSafe Firewall FR328S User Manual Page 106