Dents[5] is a modular DNS server that is intended as a drop in replacement for BIND[13].
Dents allows zones to be mounted in the name space much in the same way that UNIX allows partitions to be mounted in a directory structure. Just as different mounted partitions in a directory structure may have different file systems controlled by different portions of code in the kernel, Dents allows different zones types, controlled by driver modules.
Access to a the root name server is analogous to the root (/) directory in a UNIX directory structure. Dents allows this zone to be mounted and resolved using the driver module mod_recursive. BIND for one uses RFC 1035[19] style zone files. This is supported in Dents by mounting a zone using the mod_stddb driver module.
One advantage of being able to use different driver modules is that arbitrary modules may be defined. Driver modules that access zone information stored in a relational data base or produce standard mappings from an IP address to a hostname for dialup pools are two example applications.
Super Sparrow implements a Dents driver module, mod_supersparrow, that allows Dents to return results based on information from BGP speaking route-servers. In this way the IP address returned for a hostname lookup may be governed by the BGP-based global loadbalancing algorithm implemented by Super Sparrow. Details of how client-server interactions work in such a setup are described in section 4.1.