Hostname and underscore

April 14, 2009 at 3:20 pm · Filed under Uncategorized ·Tagged admin, dns, sys, sysadmin, system, system administration, tips, tips and tricks

RFC 952 and RFC 1123 explains the rules for choosing a hostname. I noticed recently that a lot of admins (including me) are using underscores in hostnames, but this doesn’t follow RFCs. This can lead to strange behaviours, such as mail not delivered with an RFC compliant mail server to an MX that have underscores in its name …
I noticed that because the “hostname” command on linux can set the hostname of a system, but the command doesn’t accept underscores. So guys, don’t use underscores !

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