func normalizeDNSName(dnsName string) string {
	s := strings.TrimSpace(strings.ToLower(dnsName))
	if !strings.HasSuffix(s, ".") {
		s += "."
	}
	return s
}
func normalizeDNSName(dnsName string) string {
	s := strings.TrimSpace(strings.ToLower(dnsName))
	if !strings.HasSuffix(s, ".") {
		s += "."
	}
	return s
}
// normalizeDNSName converts a DNS name to a canonical form, so that we can use string equality
// it: removes space, converts to lower case, ensures there is a trailing dot