Third-level Domain Naming Conventions

For information related to this topic refer to:

• General Rules for URL Assignment

Naming Conventions 

The network at Carnegie Mellon is shared by the many departments within the university. Third-level domain names, which appear before the ".cmu.edu" part of a computer's full name, are generally used to indicate which department owns or administrates a machine.

The following illustrates the parts of a typical computer name at Carnegie Mellon:

machine-name.org-name.cmu.edu

For example:

synergy.as.cmu.edu
hamlet.andrew.cmu.edu

In the first example above, "as" is the third-level domain, indicating that this machine is administrated by Administrative Systems). In the second example, "andrew" is the third-level domain for this computer. Computers that are not assigned to another third-level domain are generally assigned to the "andrew" third-level domain by default (student-owned computers in residence halls are assigned to the "res" third-level domain by default).

To further illustrate how third-level domain names work, compare your computer name to a home address. Universities and other educational institutions all reside in the "edu" domain. If we consider the "edu" domain to be analogous to a state, like Pennsylvania, we can consider "cmu" to be something like a city within that state and the third-level domain name to be a street within that city. Machine names, like "hamlet", "synergy", etc., are like the houses along those streets.

Because the changes to the third-level domain name structure require coordination with multiple departments on campus, we try to minimize the amount of modifications by imposing some restriction on those changes. These restrictions also ensure that the third-level domain structure remains somewhat manageable and easily maintained.

Using the home address analogy explained above, adding houses to an existing street is fairly simple, but creating a new street requires a great deal more work. Also, adding new streets on which only one house will be built is somewhat expensive and creates more maintenance work than necessary.