def compare_subdomain_of_zone(n1, n2)
return 0 if (!n1 && !n2)
return -1 if !n1
return 1 if !n2
name1 = n1.name
name2 = n2.name
return 0 if ((name1.labels.length <= @soa.name.labels.length) &&
(name2.labels.length <= @soa.name.labels.length))
return -1 if name2.labels.length <= @soa.name.labels.length
return 1 if name1.labels.length <= @soa.name.labels.length
name1 = lose_n_labels(name1, @soa.name.labels.length)
name2= lose_n_labels(name2, @soa.name.labels.length)
return ((name1.labels[name1.labels.length-1]) <=> (name2.labels[name2.labels.length-1]))
end