Actually I encountered this problem with CentOS "7.0-1406" but because I could
fix the faulty python script myself (easily) I thought to post the solution as
well here.

When running:
~]# ipa-server-install
...
Server host name [becke-ch--directory--s0-v1.becke.ch]:
becke-ch--directory--s0-v1.becke.ch
...
I get:
Invalid hostname 'becke-ch--directory--s0-v1.becke.ch', only letters, numbers,
'-' are allowed. DNS label may not start or end with '-'

BUT when I enter:
Server host name [becke-ch--directory--s0-v1.becke.ch]:
becke-ch-directory-s0-v1.becke.ch
Then it runs fine.

http://bugs.centos.org/view.php?id=7818

Name        : ipa-server
Arch        : x86_64
Version     : 3.3.3

SOLUTION:
---------
Replace regex repetition character "?" with "*": See:
]# diff util.py /usr/lib/python2.7/site-packages/ipalib/util.py
231c231
< label_regex =
r'^[%(base)s%(extra)s]([%(base)s%(extra)s%(middle)s]?[%(base)s%(extra)s])*$' \
---
> label_regex =
r'^[%(base)s%(extra)s]([%(base)s%(extra)s%(middle)s]*[%(base)s%(extra)s])*$' \