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Chapter 11 Interfaces
ZyWALL USG 50 User’s Guide
269
• IP address - If the DHCP client’s MAC address is in the ZyWALL’s static DHCP
table, the interface assigns the corresponding IP address. If not, the interface
assigns IP addresses from a pool, defined by the starting address of the pool
and the pool size.
The ZyWALL cannot assign the first address (network address) or the last
address (broadcast address) in the subnet defined by the interface’s IP address
and subnet mask. For example, in the first entry, if the subnet mask is
255.255.255.0, the ZyWALL cannot assign 50.50.50.0 or 50.50.50.255. If the
subnet mask is 255.255.0.0, the ZyWALL cannot assign 50.50.0.0 or
50.50.255.255. Otherwise, it can assign every IP address in the range, except
the interface’s IP address.
If you do not specify the starting address or the pool size, the interface the
maximum range of IP addresses allowed by the interface’s IP address and
subnet mask. For example, if the interface’s IP address is 9.9.9.1 and subnet
mask is 255.255.255.0, the starting IP address in the pool is 9.9.9.2, and the
pool size is 253.
• Subnet mask - The interface provides the same subnet mask you specify for the
interface. See IP Address Assignment on page 266.
• Gateway - The interface provides the same gateway you specify for the
interface. See IP Address Assignment on page 266.
• 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.
Table 72 Example: Assigning IP Addresses from a Pool
START IP ADDRESS POOL SIZE RANGE OF ASSIGNED IP ADDRESS
50.50.50.33 5 50.50.50.33 - 50.50.50.37
75.75.75.1 200 75.75.75.1 - 75.75.75.200
99.99.1.1 1023 99.99.1.1 - 99.99.4.255
120.120.120.100 100 120.120.120.100 - 120.120.120.199