code: func IsFQDN(domain string) bool {
  	// TODO(mpl): there's probably a regexp for all this...
  	if domain == "localhost" {
  		return false
  	}
  	if !strings.Contains(domain, ".") {
  		return false
  	}
  	if strings.Contains(domain, "/") {
  		return false
  	}
  	if net.ParseIP(domain) != nil {
  		return false
  	}
  	return true
  }
docs: // IsFQDN reports whether domain looks like a fully qualified domain name.