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Old 19th July 2013
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jggimi jggimi is offline
More noise than signal
 
Join Date: May 2008
Location: USA
Posts: 7,977
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You're not an idiot; these are not idiotic questions.

"my.domain" is just an easy way to pick a local domain name that would never be a valid Internet domain name. I've had systems where I used "local" instead. It's entirely up to you what you pick. The reason to pick something invalid is to speed up any responses to DNS resolution requests. A domain that is an invalid Top Level Domain (.com, .edu, .uk, .org, .tv) gets a real quick negative response from servers, including the Internet root servers.

You don't need a local domain name. You can name your computers without them. Since they're not directly addressable from the Internet, using a local domain name is a convenience for you and your network. You might have multiple local domains, as well.

Take a look at the resolv.conf(5) man page. You'll see two options that can help with local domain name use: domain and search.

As the number of devices on your network grows, you may find it easier to have a local Domain Name Server rather than keeping /etc/hosts files in sync on all your platforms. These not only provide local name resolution, they can also act as caches for "real" Internet facing Domain Name Servers such as the servers provided by your ISP.

A local Domain Name Server can be used whether or not you have .my.domain or .local or .frcc or just computers with names like "John" and "Marsha".
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