Modern Network Programming

Application SHOULD support BOTH IPv6 and IPv4
Same source / binary should run on various configurations / envirionments
Some may not have IPv6 stack
Some may have IPv6 stack but no connectivity 
Eventually, some may no have IPv4 stack
Modern programming style helps us
getaddrinfo(), getnameinfo(), getifaddrs()
clean, generic and abstract interface
Independent from protocols
Easier to support more protocols
Less knowledge on protocols