lib/respect/format_validator.rb
def validate_hostname(value)
      match_data = HOSTNAME_REGEXP.match(value)
      if match_data
        value.split('.').each_with_index do |label, i|
          unless label.length <= 63
            raise ValidationError,
                  "hostname's #{i.ordinalize} label '#{label}' is not less than 63 characters in '#{value}'"
          end
        end
      else
        raise ValidationError, "invalid hostname '#{value}'"
      end
    end
def validate_hostname(value)
      match_data = HOSTNAME_REGEXP.match(value)
      if match_data
        value.split('.').each_with_index do |label, i|
          unless label.length <= 63
            raise ValidationError,
                  "hostname's #{i.ordinalize} label '#{label}' is not less than 63 characters in '#{value}'"
          end
        end
      else
        raise ValidationError, "invalid hostname '#{value}'"
      end
    end
Validate that the given string _value_ describes a well-formed
 host name as specified by RFC 1034.
 (see http://www.rfc-editor.org/rfc/rfc1034.txt)