> First, if your host is actually communicating with any kind of ip-based > network, it is quite certain, that 127.0.0.1 simply isn't his IP > address. And, at least for me, that's a fairly good reason. Indeed. It does seem like a bad idea to have a single host using loopback, while the rest of the network refers to it by it's real IP address. > Second, sendmail had the habit of breaking if your hostname was mapped > to 127.0.0.1, but I stopped using sendmail a decade ago, so I can't > verify this. :) The reason this came up is because one of our end-users requested such a setup in the /etc/hosts file, and I didn't think it was a good idea. Seems it would be better to fix the application(s) that require the data to use the real network IP address.