gdnsd is an Authoritative-only DNS server. The initial g stands for Geographic, as gdnsd offers a plugin system for geographic (or other sorts of) balancing, redirection, and service-state-conscious failover.
gdnsd is written in C, and uses pthreads with libev and liburcu to attain very high performance, low latency service. It does not offer any form of caching or recursive service, and does not support DNSSEC. There's a strong focus on making the code efficient, lean, and resilient. The code has a decent regression testsuite with full branch coverage on the core packet parsing and generation code, and some scripted QA tools for e.g. valgrind validation, clang-analyzer, etc.
The geographically-aware features also support the EDNS Client Subnet spec from RFC 7871 for receiving more-precise network location information from intermediate shared caches.