bind - How to prevent sub-domain 'hijacking' on the same DNS server?

I'm trying to understand how (or if) a DNS server differentiates between a sub-domain setup as a zone and one setup as a record within a domain zone on the same server.

Say I were to create a DNS zone on a DNS server for a domain e.g. example.com.

What is to stop someone from creating another zone, test.example.com, on the same server and 'hijacking' that sub-domain of the domain?

When a DNS request is made to the name server for test.example.com, will the DNS server return:

• The main A record of the test.example.com zone or



• The test.example.com A record in the example.com zone

(and if the A record for test.example.com doesn't exist in example.com will it return no such record or continue onto the zone of test.example.com)

Is there any way of preventing the sub-domain zone from responding without moving the domains to their own unique name server? How do the likes of ZoneEdit and Amazon's Route53 handle this?

(If a sub-domain was hosted on a separate server the master zone for example.com would have to delegate the sub-domain to that separate server, correct? (as per this Technet article).)