D("foo.com","none",
    A("@","1.2.3.4", TTL("300s")),
    A("a","1.2.3.5", TTL("300")),
    A("b","1.2.3.6", TTL("3m")),
    A("c","1.2.3.7", TTL("3h")),
    A("d","1.2.3.8", TTL("3d"))
);