Check that name is DNS label: An alphanumeric (a-z, and 0-9) string,
    with a maximum length of 63 characters, with the '-' character allowed
    anywhere except the first or last character, suitable for use as a hostname
    or segment in a domain name

def _is_dns_label(name):
    ''' Check that name is DNS label: An alphanumeric (a-z, and 0-9) string,
    with a maximum length of 63 characters, with the '-' character allowed
    anywhere except the first or last character, suitable for use as a hostname
    or segment in a domain name '''

    dns_label = re.compile(r"""^[a-z0-9][a-z0-9\.-]{1,62}$""")
    if dns_label.match(name):
        return True
    else:
        return False