If you want to use a CNAME to create a pointer for a server on your network, you must create a new record on DNS server of the type CNAME. But you might experience some issues when you want to use the new alias CNAME. This problem is caused by a restrict name checking. So you must create a new key on registry to solve this.
The new key will disable the restrict name checking see the KB with all details and support.
http://support.microsoft.com/kb/281308/en-us
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