Minor: It seems that the NoProxy directive can handle multiple arguments seperated by a comma. Major: When you use the <Directory proxy:*> directive as distributed with the last version(s). There is an error with the handling of the allow from directive. It doesn't do DNS ! So you can't use canonical names. It works when you use IP#'s. Is this a bug in the proxy module or did something else broke? Maybe it's best you forward this to the apache development team...?
It seems that this bug is not actualy in the proxy module (IMHO). The symptom is available in all Allow from directives and perhaps similars. I just found out it had problems with the allow from because it stoped allowing an internal lan machine from accessing wich it allowed before with the same config.
this is actually a feature. DNS lookups are off in apache for performance reasons. Otherwise, each access would result in a DNS lookup, which is VERY SLOW relative to other operations. You can enable them though if you wish. Please read the apache manual.