WebSphere Application Server name servers are an implementation of the CORBA CosNaming interface. WebSphere Application Server provides a JNDI implementation that you can use to access CosNaming name servers through the JNDI interface. CosNaming provides the server-side implementation and is where the name space is stored. JNDI essentially provides a client-side wrapper of the name space stored in CosNaming, and interacts with the CosNaming server on behalf of the client.
I copied this diagram from System Management Handbook red book, that explains the Naming service architecture