BIND is implemented as a named daemon program
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Written by Robert on April 14, 2008 – 4:31 pm
Paul Mockapetris developed the first software implementing the DNS system in 1982 while working for USC. The vast majority of DNS systems currently used employ some version of the Berkeley Internet Name Domain software (BIND). Originally developed at Berkeley (~1984), then at DEC, BIND is now controlled by the Internet Science Corporation. It has a rather odd version numbering system jumping from version 4.9 to 8, and now 9. Hopefully, most DNS systems are running version 8.2 or 9.2. On Unix/Linux, BIND is implemented as the named daemon program. If you do become responsible for running a DNS system, your responsibilities will include keeping your copy of named up to date, by downloading the latest updates, and maintaining data in ‘zone’ files and configuration files for use by the stub resolver and the named process. If you have access to a Unix system on the Internet, it is worth having a look at the files that hold the data for its name server processes (these files should be publicly readable; most will be in the /etc directory).
There are two files used by the stub resolver – /etc/hosts and /etc/resolv.conf. The hosts file simply lists the IP addresses and names of a few heavily used local server machines. The resolv.conf file provides data on the IP addresses of machines that run the named process (the name server) that the stub resolver can call upon; these appear as ‘nameserver’ entries along with their IP addresses. The file also provides information on how to sort out ‘nicknames’ for commonly used machines.
Names can be ‘absolute’ or ‘relative’. An absolute name is something like perl.org. – note the final ‘.’. This identifies the machine as host www in the perl sub-domain of the org sub-domain as defined in the root name servers. Relative names don’t have a final ‘.’; it is up to the stub resolver to sort them out; its behavior is controlled by configuration data. If a name does contain any ‘.’characters it is usually treated as if it were ameant to be an absolute name. Names that have no dots are most often nicknames for commonly used machines; typically, only these are processed further. The resolv.conf file may include a list of domains that can be added to a single element name (or, if desired, to any relative name). For example, suppose there is a cs sub-domain within bigcampus.edu; local servers include balin. cs.bigcampus.edu, dwalin.cs.bigcampus.edu, gandalf.bigcampus.edu and frodo. bigcampus.edu. The resolv.conf file for the cs.bigcampus.edu sub-domain could specify that the ‘search’ path include cs.bigcampus.edu and bigcampus.edu. A request specifying a server using just using the nickname ‘gandalf’would be tried as gandalf.cs.bigcampus.edu and then as gandalf.bigcampus.edu.
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