ZyXEL Communications ZyWall USG 50-H Series, User Manual

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Chapter 8 Interface
ZyWALL USG 50-H User’s Guide
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• DNS servers - The interface provides IP addresses for up to three DNS servers that
provide DNS services for DHCP clients. You can specify each IP address manually (for
example, a company’s own DNS server), or you can refer to DNS servers that other
interfaces received from DHCP servers (for example, a DNS server at an ISP). These other
interfaces have to be DHCP clients.
It is not possible for an interface to be the DHCP server and a DHCP client simultaneously.
WINS
WINS (Windows Internet Naming Service) is a Windows implementation of NetBIOS Name
Server (NBNS) on Windows. It keeps track of NetBIOS computer names. It stores a mapping
table of your network’s computer names and IP addresses. The table is dynamically updated
for IP addresses assigned by DHCP. This helps reduce broadcast traffic since computers can
query the server instead of broadcasting a request for a computer name’s IP address. In this
way WINS is similar to DNS, although WINS does not use a hierarchy (unlike DNS). A
network can have more than one WINS server. Samba can also serve as a WINS server.
PPPoE/PPTP Overview
Point-to-Point Protocol over Ethernet (PPPoE, RFC 2516) and Point-to-Point Tunneling
Protocol (PPTP, RFC 2637) are usually used to connect two computers over phone lines or
broadband connections. PPPoE is often used with cable modems and DSL connections. It
provides the following advantages:
• The access and authentication method works with existing systems, including RADIUS.
• You can access one of several network services. This makes it easier for the service
provider to offer the service
• PPPoE does not usually require any special configuration of the modem.
PPTP is used to set up virtual private networks (VPN) in unsecure TCP/IP environments. It
sets up two sessions.
1 The first one runs on TCP port 1723. It is used to start and manage the second one.
2
The second one uses Generic Routing Encapsulation (GRE, RFC 2890) to transfer
information between the computers.
PPTP is convenient and easy-to-use, but you have to make sure that firewalls support both
PPTP sessions.