) in its name, why am I having trouble accessing network services?

ARCHIVED: If my computer has an underscore ( _ ) in its name, why am I having trouble accessing network services?

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The underscore is not a legal character for use in hostnames. As defined in RFC 822, the only legal characters are the following:

Alphanumeric ( a-z and 0-9 ): Both uppercase and lowercase letters are acceptable, and the hostname is case insensitive. In other words, dvader.empire.gov is identical to DVADER.EMPIRE.GOV and Dvader.Empire.Gov .

( and ): Both uppercase and lowercase letters are acceptable, and the hostname is case insensitive. In other words, is identical to and . Hyphen ( - ): Neither the first nor the last character in a hostname field should be a hyphen.

( ): Neither the first nor the last character in a hostname field should be a hyphen. Period ( . ): The period should be used only to delimit fields in a hostname (e.g., dvader . empire . gov ) .