Reference Manual

NAME

dnsmap - turn DNS Mapping on or off

dnsmap [ifn [on|off]]

DNS mapping is a mechanism which allows hosts on a private LAN to use DNS Services even if the adddress of an actual DNS Server is unknown. The mechanism works as follows:
 

When DNS mapping is on for a particular private interface, all DNS requests sent by private hosts to NAT32's IP address are redirected to a DNS Server known to NAT32 (see setns). When a response arrives, NAT32 forwards it to the private host after adjusting its source address so that it appears to have come from NAT32. Private hosts that are DHCP-configured will automatically receive the correct DNS settings.

When DNS mapping is off for a particular interface, private hosts on that network may still be using NAT32's private IP Address as their DNS Server. A DNS Forwarding daemon dnsfd or wdnsfd should then be started so that such hosts continue to be able to resolve names. The dnsfd and wdnsfd listen at UDP Port 53 and forward DNS requests to the configured DNS Server.

If DNS Mapping is permanently off, the DHCP Server should be configured to propagate the "real" DNS Server address to clients. This can be done with the command: dhcpd ifn real on and a forwarding daemon is then unnecessary.

DHCP Server, DNS Resolvers and Forwarders, Interface Configuration, Name Server, Set Name Server