But this may be a serious error. For the ideas outlined below, I do not claim that multiple addresses per host is the only or even necessarily the best way to accomplish the goal. I do claim that my ideas are at the very least plausible, and that I expect that many of them will be tried. Encoding Services More and more often, services are being encoded in the host name. In some cases it would be a very good idea.
Security is another reason, in some cases.
An attacker can go after the DNS, in that case. But that, of course, leads to all the usual headaches when the location of the service changes. If the address for the service could be held constant, there would be much more freedom to move it to another machine. One way to do that is by assigning the serving host a secondary address. A related notion comes from the need to offer different views of a service from a single host.