Proxy Servers in a ICP hierarchy.

On the parent server "Cache Hierarchy Server", "Access Control List"
are 2 possibilities: IP or host name. In my environment by hostname
not work. On the child proxy console, the parent´s status is "DOWN".

Does somebody knows if this is a bug or a feature?
I would like to operate with hostnames, it is easier.

PS: The child proxy server is possible to link to his parent by
but only by full name (hostname.domain).

Best Regards,
Valentin Rata.