Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!decwrl!stanford.edu!csli!gandalf From: gandalf@csli.Stanford.EDU (Juergen Wagner) Newsgroups: comp.protocols.tcp-ip.domains Subject: Re: Creating a domain alias Message-ID: <18416@csli.Stanford.EDU> Date: 26 Mar 91 08:45:25 GMT References: Distribution: comp Organization: Center for the Study of Language and Information, Stanford U. Lines: 43 Kimmo.Suominen@lut.fi (Kimmo Suominen) writes: >Well, it is not recommended to use an alias in mail addresses. In some cases, it is *desirable* to have CNAMEs in mail addresses. If a site with a large number of machines and users decides to promote a single, uniform addresssing schema for all users to the rest of the world, there are three alternatives: - mailbox@somehost.our.domain (somehost being a real host) This has the disadvantage of having to be changed when the mail service is moved to another machine. - mailbox@our.domain (our.domain being the local domain name) Having MX for our.domain point to somehost.our.domain, this is a general solution. The MX host can decide what to do with mail on a local basis. - mailbox@virtual.our.domain (virtual being a non-existent host name) Entering MX or CNAME records for the virtual host provides the same functionality as the second solution. Users have to type more, though. As the third example shows, CNAMEs provide an easy way of calling hosts by more than one name. This allows people to call hosts not only by their canonical name, but also by abstract names designating some service or function (e.g. ftp.iao.fhg.de, nntpserver.iao.fhg.de, ...). As for having multiple names pointing at the same address, I am not sure whether that's recommended. However, I found it useful in situation where hosts have multiple interfaces, so I can refer to the interfaces by distinct names: apatix IN A 129.233.6.1 IN A 192.44.21.1 apatix_qe0 IN A 129.233.6.1 apatix_dmv0 IN A 192.44.21.1 with all addresses pointing to the canonical host name 'apatix'. --Juergen Wagner (gandalf@csli.stanford.edu, a.k.a. wagner@iao.fhg.de)