Enterprise Manager Database Control on host with an underscore in it's name

Question

I know it sounds awkward, but Enterprise Manager is refusing to be set up because of an underscore in the server name:

C:\>emca -deconfig dbcontrol db -repos drop

STARTED EMCA um 30.05.2012 13:21:49
EM-Konfigurationsassistent, Version 11.2.0.0.2 Production
Copyright (c) 2003, 2005, Oracle.  All rights reserved. Alle Rechte vorbehalten.

...

SCHWERWIEGEND:  Ungültiger Host-Name vm_scotty11.xxnet.de. Host-Name darf keinen Unterstrich ('_') enthalten.
Weitere Einzelheiten finden Sie in der Log-Datei in c:\app\Administrator\cfgtoollogs\emca\PRJ\emca_2012_05_30_13_21_49.log.
Die Konfiguration konnte nicht abgeschlossen werden. Weitere Einzelheiten finden Sie in der Log-Datei in c:\app\Administrator\cfgtoollogs\emca\PRJ\emca_2012_05_30_13_21_49.log.

Has someone worked around this issue or can provide a documentation link which explains why this happens?

I know that there must have been warning messages upon installation of OS and DB but I still need to see it written in the docs in order to convince and make the point that the host name has to be changed.

Answer 1

This is happening because an underscore in a hostname is not a valid character according to the RFC.

"The Internet standards for protocols mandate that component hostname labels may contain only the ASCII letters 'a' through 'z' (in a case-insensitive manner), the digits '0' through '9', and the hyphen ('-')."