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3.1 Internet and the Domain Name System     continued...

If your local network cannot translate the name, you will get an ``unknown host'' error message. If you know the numeric address, try it:

% rlogin 129.59.130.21

Figure 5: Top Level Internet Domains.

The symbolic name of a site is determined by a naming standard known as the domain name system. Each field in a symbolic address corresponds to a single domain. The first field is a host name, which identifies a single computer. The last

field is a top level domain. In between are department names, organization names, etc. in order of increasing generality. In our example, compsci.cas.vanderbilt.edu is a host named compsci in the College of Arts and Sciences at Vanderbilt University, which is an educational institution. The six top level domains in the US and some sample addresses are listed in Figure 5. Symbolic addresses of sites outside the US end with a two-letter country code. Common country codes are also listed in Figure 5. There is a slow movement toward a naming standard that includes geographic information for sites within the US, also, but it is proceeding about as slowly as the conversion to the metric system. As new sites apply for Internet names many are given these new style names. For example, a name being considered for the Springfield Public School District is sps.lane.or.us (Springfield Public Schools, Lane County, Oregon, US).