cache server with authoritative answer

[pyh at mail.nsbeta.info]

The book "Pro DNS and BIND" says: 

If the caching server obtains its data directly from an authoritative DNS, 
then it too will respond as authoritative. Ohterwise, if the data is 
supplied from its cache, the response is nonauthoritative. 

So this means even for a cache only server it can answer with authoritative 
response? I have been thinking the cache only server shouldn't do this. 

Regards.