DNSControl (https://dnscontrol.org https://dnscontrol.org) supports split horizons as of a few days ago! https://github.com/StackExchange/dnscontrol/releases/t

DNSControl (https://dnscontrol.org https://dnscontrol.org) supports split horizons as of a few days ago! https://github.com/StackExchange/dnscontrol/releases/tag/v3.7.0 https://github.com/StackExchange/dnscontrol/releases/tag/v3.... (and if I do say-so myself... the way we implemented it is pretty darn elegant)