Subdomain and Web Server Names

This document describes the policy and conventions for subdomains and web servers.

Subdomains

Internet names are used to identify hosts (computer systems, workstations, post office systems, and other devices) on the Internet. Domains are groups of Internet names.

Organizational Subdomains

The Internet domain name for the University of California at Berkeley is Berkeley.EDU. CNS evaluates requests for new subdomains on a case-by-case basis. With one exception, we will create a new subdomain only if three conditions are satisfied:

1. the subdomain represents a unit that is officially recognized by the University;
2. the unit has an administrative structure such that it makes sense to name machines within the requested subdomain (i.e. we expect that there is some common system administration to all the hosts in a subdomain); and
3. we believe that there will be a reasonable number of host names within the requested subdomain within a one-year period.

Exception for www hostnames

Many web servers have hostnames beginning with www. There is no standard that requires this, and it often makes more sense to use a descriptive hostname related to the purpose of the server. Nevertheless, it's a fact of life on the Internet today that many users expect to see www in a web server hostname, and get confused if it isn't there. For this reason, CNS permits the following exception to the above conditions:

1. The subdomain contains exactly one host, named www, and
2. the name of the subdomain must be a valid hostname within the Berkeley.EDU domain or one of its organizational subdomains.

When the conditions for either type of subdomain are met, we will create and maintain the new subdomain.

A subdomain name may be requested by sending an email message to hostmaster@nic.berkeley.edu. The request should come from or be approved by the manager of the administrative unit requesting the subdomain name.

Domain names are not case significant. Names may be all lower case, all upper case, or mixed case. For example, Internet applications will interpret violet.berkeley.edu and violet.Berkeley.EDU to be the same host name. The following mixed-case style is recommended to improve the readablity of names in the .Berkeley.EDU subdomain:

• Capitalize the suffix .EDU.
• Capitalize first letter of words, for example, Berkeley.EDU.
• Capitalize all letters in an acronym, for example, EECS.Berkeley.EDU.
• Capitalize first letter of each abbreviation, partial word, or word in a composite subdomain name, for example, ResHall.Berkeley.EDU.
• Leave the short name of a host in lower case, for example violet.Berkeley.EDU.

Web Server Names

WWW servers must have Internet host names. WWW server names at UC Berkeley must conform to Internet host naming standards:

• They may contain only letters, numbers, hyphens ("-") and periods (".").
• A hyphen in a name may not be followed by a period ("-.").
• If the name is also used for email:
• the first character of the name must begin with a letter, and
• the full name must be 63 characters or less in length.
• If the name is not used for email:
• the first character of the name must be a letter or a number.
• Alias names (CNAME record) may only be defined for Internet names. It is not possible to define an alias name (CNAME record) for a port number, file or directory name.

There are resource and software limitations for Internet names:

• There is a limit on the number of CNAME records that may be defined pointing to a single Internet host name.
• There is a limit to the number of available Internet addresses (numbers) on a segment of the network. Thus, there is a limit to the number of Internet addresses that maybe registered for a single Internet host.

It is recommended that WWW server names at UC Berkeley:

• conform to one of the following formats:
  • something.berkeley.edu simply the name of the site for units without registered subdomain names.
  • www.unit.berkeley.edu or something.unit.berkeley.edu for units with registered subdomain names.
• not contain the abbreviation ucb. Names containing ucb are considered to be redundant since UC Berkeley is identified by the domain name .Berkeley.EDU.
• be registered as alias names (CNAME records) to allow the servers to be easily moved.

Web server names in the form www.something.Berkeley.EDU or www.something.unit.Berkeley.EDU (where something is not an organizational subdomain) are strongly discouraged.

Requests for WWW server names may be sent to hostmaster@nic.berkeley.edu Requests for alias names for an existing system on the Internet should be sent by the system administrator for that system.

Requests for "IP aliases" (more than one name/number pair on the same network segment for the same host) will be evaluated on a case-by-case basis.