It is possible to delegate stuff to DNS (and some DNSSEC patches were recently merged - see http://dot-bit.org/forum/viewtopic.php?f=5&t=1434&p=7718), but even if records are delegated to DNS namecoin doesn't know or care what's there.

Namecoin is essentially a key-value store. A .bit domain is a key under Namecoin's d/ namespace, and the value is some JSON data describing the domain, per this spec: http://dot-bit.org/Namespace:Domain_names_v2.0

Edit: Actually, to further clarify, Namecoin itself doesn't know/care about the semantics of what data is stored for a domain. The data is interpreted by applications that act as application layer bridges to other resolver protocols. Check out nmcontrol and NamecoinToBind for examples.