public String
getErrorString() {
	checkDone();
	if (error != null)
		return error;
	switch (result) {
		case SUCCESSFUL:	return "successful";
		case UNRECOVERABLE:	return "unrecoverable error";
		case TRY_AGAIN:		return "try again";
		case HOST_NOT_FOUND:	return "host not found";
		case TYPE_NOT_FOUND:	return "type not found";
	}
	throw new IllegalStateException("unknown result");
}
Returns an error string describing the result code of this lookup.
@return A string, which may either directly correspond the result code
or be more specific.
@throws IllegalStateException The lookup has not completed.
src/main/java/core/org/xbill/DNS/Lookup.java