How can I check `elasticsearch is down` condition in my service?

I have some service. I need return data from elastic search if it available or return from DB:

@Service
class DefaulUserService implements UserService {

    private final DbDao dbDao;
    private final ElasticsearchDao elasticsearchDao;

    DefaultDoctorService(DbDao dbDao, ElasticsearchDao elasticsearchDao) {
        this.dbDao= dbDao;
        this.elasticsearchDao= elasticsearchDao;
    }

    @Override
    public List<User> findAll() {
       if(elasticsearch is down){
             return dbDao.findAll();
        } else {
             return elasticsearchDao.findAll();
       }
    }
}

How can I check the elasticsearch is down condition in my service?

If it's truly down, elasticsearchDao.findAll(); should surely raise an exception, right?

@Service
class DefaultUserService implements UserService {

    private final DbDao dbDao;
    private final ElasticsearchDao elasticsearchDao;

    DefaultDoctorService(DbDao dbDao, ElasticsearchDao elasticsearchDao) {
        this.dbDao= dbDao;
        this.elasticsearchDao= elasticsearchDao;
    }

    @Override
    public List<User> findAll() {
        try {
            return elasticsearchDao.findAll();
        }
        catch(Exception e) {
            return dbDao.findAll();
        }
    }
}

Obviously you'd have to pick a more appropriate type of exception to catch.