Counterpoint: .internal is much easier to understrand, .intra sounds like a reference to "intranet" as opposed to "internet". That's terminology networking people would use, but .internal is likely something both non-tech and tech people would intuitively understand.
I don't think `.internal` to be intuitively understandable either. In spite of other shortcomings, `.home` and `.corp` convey its private-use natures much better than `.internal`. (But they won't be suitable for anything other than that.)
