ZyXEL Communications NBG420N User Manual

 Chapter 10 DHCP

NBG420N User’s Guide

The DHCP table shows current DHCP client information (including IP Address, Host Name 
and MAC Address) of network clients using the NBG420N’s DHCP servers.
Configure this screen to always assign an IP address to a MAC address (and host name). Click 
Network > DHCP Server > Client List. 

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You can also view a read-only client list by clicking the DHCP Table (Details...) 
hyperlink in the Status screen. 

The following screen displays.

DNS Server

DNS Servers 

Assigned by DHCP 

Server 

The NBG420N passes a DNS (Domain Name System) server IP address (in the 

order you specify here) to the DHCP clients. The NBG420N only passes this 

information to the LAN DHCP clients when you select the Enable DHCP Server 

check box. When you clear the Enable DHCP Server check box, DHCP service 

is disabled and you must have another DHCP sever on your LAN, or else the 

computers must have their DNS server addresses manually configured.

First DNS Server
Second DNS 

Server
Third DNS Server 

Select From ISP if your ISP dynamically assigns DNS server information (and 

the NBG420N's WAN IP address). The field to the right displays the (read-only) 

DNS server IP address that the ISP assigns. 
Select User-Defined if you have the IP address of a DNS server. Enter the DNS 

server's IP address in the field to the right. If you chose User-Defined, but leave 

the IP address set to 0.0.0.0, User-Defined changes to None after you click 

Apply. If you set a second choice to User-Defined, and enter the same IP 

address, the second User-Defined changes to None after you click Apply. 
Select DNS Relay to have the NBG420N act as a DNS proxy. The NBG420N's 

LAN IP address displays in the field to the right (read-only). The NBG420N tells 

the DHCP clients on the LAN that the NBG420N itself is the DNS server. When a 

computer on the LAN sends a DNS query to the NBG420N, the NBG420N 

forwards the query to the NBG420N's system DNS server (configured in the 

WAN > Internet Connection screen) and relays the response back to the 

computer. You can only select DNS Relay for one of the three servers; if you 

select DNS Relay for a second or third DNS server, that choice changes to None 

after you click Apply. 
Select None if you do not want to configure DNS servers. If you do not configure 

a DNS server, you must know the IP address of a computer in order to access it.

Apply

Click Apply to save your changes back to the NBG420N.

Reset

Click Reset to begin configuring this screen afresh.

Table 51   Network > DHCP > Advanced