Reference:

• Docker embedded DNS for each container: https://github.com/moby/libnetwork/blob/master/resolver.go
• Stellar internal nameserver: https://github.com/ehazlett/stellar/blob/ec07fa69e54e767df7eed88e731437bdef5d31ef/services/nameserver/dns.go