Servers cache the original values of modified sections of rogue servers Authentication Trees. The combination of protocols in clients and servers ensures that users can choose which filters they want to subscribe to. Companies may be satisfied with the subset of names that survive the policies of a monopoly unaudited root server. People who want more robust names can use the root namespace explicitly. For efficiency you probably want namespace servers to do the auditing.
Users can of course independently audit also.
Imagine a binary tree representing a namespace with names as the leaf nodes. The parent of a leaf node is the hash of the pair of names below it. The parent of that node with it's neighbor is the hash of it and the neighbor hash, and so on up to the root which is the master hash of all the hash of hashes of names down to the leaves. Fortunately Merkle's patent has expired.