gdnsd is an Authoritative-only DNS server which does geographic (or other
sorts of) balancing, redirection, weighting, and service-state-conscious
failover at the DNS layer.
gdnsd is written in C using libev and pthreads with a focus on high
performance, low latency service. It does not offer any form of caching or
recursive service, and notably 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 emerging EDNS Client
Subnet draft for receiving more-precise network location information
from intermediate shared caches.