Cache File

The cache file is used to connect the DNS server to root servers on the Internet. The file can be any name. On many systems, the cache file is called named.ca. Other systems may call the cache file named.cache or roots.hints. The cache file is usually a standard file installed by your BIND software, which lists resource records for designated root servers for the Internet. You can obtain a current version of the named.ca file from the rs.internic.net FTP site. The following example shows sample entries taken from the named.ca file:

; formerly NS.INTERNIC.NET
;
. 3600000 IN NS A.ROOT-SERVERS.NET.
A.ROOT-SERVERS.NET. 3600000 A 198.41.0.4
;
; formerly NS1.ISI.EDU
;
. 3600000 NS B.ROOT-SERVERS.NET.
B.ROOT-SERVERS.NET. 3600000 A 128.9.0.107

If you are creating an isolated intranet, you need to create your own root DNS server until you connect to the Internet. In effect, you are creating a fake root server. This can be another server on your system pretending to be the root or the same name server.