Specifying DMZ Addresses 59Specifying the DNSSettingsIn the Other Settings section, specify the DNS Servers. Up to three DNSservers can be specified, although not all have to be used. The Firewalluses these servers to look up the addresses of machines used todownload the Web Site Filter and for the built-in DNS Lookup tool.Type the required values and click Update to save the changes. It isnecessary to restart the Firewall for these changes to take effect.Specifying DMZAddressesThe Firewall provides security by preventing Internet users from accessingmachines inside the LAN. This security, however, also prevents users fromreaching servers intended for public access, such as a Web or e-mailserver, which are crucial for effective Internet use.In order to allow such services, the Firewall comes with a specialDemilitarized Zone (DMZ) port which you use for setting up publicservers. The DMZ is located between the local network and the Internet.Servers on the DMZ are publicly accessible, but they are protected fromattacks such as SYN Flooding and Ping of Death. Use of the DMZ port isoptional and you do not have to connect it.3Com recommends that you use the DMZ port as an alternative to PublicLAN Servers or to putting these servers on the WAN port where they arenot protected and not accessible by users on the LAN unless intranetfeatures are enabled.DUA1611-0AAA02.book Page 59 Thursday, August 2, 2001 4:01 PM
