TCP/IP Configuration and Management Manual

Configuration Reference
TCP/IP Configuration and Management Manual—427132-004
A-8
Domain Name Server Files
All servers must have a line in the boot file to prime the domain name server’s cache:
cache . root-cache-file-name
For example:
cache . $SYSTEM.ZTCPIP.NAMEDCA
Note that the period (.) between the keyword cache and the root-cache-file-
name is required. There is no default cache file.
All cache files listed are read in at the NAMED startup (boot) time. Any values still valid
are reinstated in the cache, and the root name server information in the cache files is
always used. For information on cache files refer to Cache Initialization, later in this
section.
Forwarders
Forwarders are the catch-all name servers. Any server can use forwarders. A
forwarder is another server capable of processing recursive queries and willing to try to
resolve queries on behalf of other systems. The forwarder command specifies
forwarders by Internet address, as follows:
forwarder [internet-addr [internet-addr...]]
For example:
forwarder 128.33.0.12 128.33.0.14
There are two reasons for using forwarders:

The other systems may not have full network access and may be prevented from
sending any IP packets into the rest of the network; such systems must rely on a
forwarder that does have access to the full net.

The forwarder sees a union of all queries as they pass through the server;
therefore, the forwarder builds up a rich cache of data compared to the cache in a
typical workstation name server. In effect, the forwarder becomes a super-cache
that all hosts can benefit from, thereby reducing the total number of queries from
that site to the rest of the network.
Slave Mode
Slave mode is used if forwarders provide the only possible way to resolve queries due
to lack of full net access, or if you wish to prevent the name server from using
something other than the listed forwarders. Slave mode is activated by entering the
following command:
slave
Enter this command in the boot file. If you use a slave, you must specify forwarders.
When in slave mode, the server forwards each query to each forwarder until it finds an
answer or exhausts the list of forwarders.