'Update the given CNAME record in this Zone to a new value, ttl,
and identifier.  Returns a Status object.
Will throw TooManyRecordsException is name, value does not match
a single record.'

def update_cname(self, name, value, ttl=None, identifier=None, comment=''):

    name = self.route53connection._make_qualified(name)
    value = self.route53connection._make_qualified(value)
    old_record = self.get_cname(name)
    ttl = (ttl or old_record.ttl)
    return self.update_record(old_record, new_value=value, new_ttl=ttl, new_identifier=identifier, comment=comment)
