UDP组播是否可以在离线时成功完成？

Question

关于UDP多播的演示，当我想测试代码是否正确时，我发现失败了，但我认为不是代码的问题。我的虚拟机是离线的，所以我想是否udp不能多播时机器离线了吗？ 这是我的代码：

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="col-md-3 col-sm-4 offcanvas-xs" id="navMenu">
  <div class="sidebar-nav">
    <div class="navbar navbar-default" role="navigation">
      <ul class="nav navbar-nav mainNav">
        <img id="logo" class="img-responsive hidden-xs" src="assets/img/logo2.jpg" />
        <li class="link">
          <a href="#home">Home</a>
        </li>
        <li class="link">
          <a href="#aboutSection">About</a>
        </li>
        <li class="filter" data-filter=".category-1">
          <a href="#">Animation</a>
        </li>
        <li class="filter" data-filter=".category-2">
          <a href="#">Commercial</a>
        </li>
        <li class="filter" data-filter=".category-3"><a href="#">Documentary</a>
        </li>
        <li class="filter" data-filter=".category-4">
          <a href="#">Film</a>
        </li>
        <li class="filter" data-filter=".category-5">
          <a href="#">Music</a>
        </li>
        <li class="filter" data-filter=".category-6">
          <a href="#">Video Games</a>
        </li>
        <li class="link">
          <a href="#services">Services</a>
        </li>
      </ul>
    </div>
  </div>
</div>

<div class="contentWrap">
  //content
</div>

<div id="portfolio">

</div>

//this is for receive
int main(int argc,char **argv) //My Multicast address is 224.0.0.88
{
    int udpsocket;
    int res;
    char buf[50];
    struct sockaddr_in saddr;
    struct sockaddr_in raddr;
    bzero(&saddr,sizeof(saddr));
    bzero(&raddr,sizeof(raddr));
    // 初始化地址结构体变量
    saddr.sin_family = AF_INET;
    saddr.sin_port = htons(5001);
    saddr.sin_addr.s_addr = htonl(INADDR_ANY);

    // 定义并初始化组播的结构体
    struct ip_mreq mreq;
    bzero(&mreq, sizeof mreq);
    mreq.imr_multiaddr.s_addr = inet_addr(argv[1]);  //组播地址，D类型
    mreq.imr_interface.s_addr = htonl(INADDR_ANY);




    // 创建udp套接字
    udpsocket = socket(AF_INET,SOCK_DGRAM,0);
    if(udpsocket == -1)
    {
        perror("create udp socket failed!\n");
        return -1;
    }
    // 设置可以组播
    setsockopt(udpsocket, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                &mreq, sizeof mreq); 
    int ret = sizeof(struct sockaddr);
    // 绑定
    res = bind(udpsocket,(struct sockaddr *)&saddr,ret);
    if(res == -1)
    {
        perror("bind udp socket failed!\n");
        return -1;
    }

    while(1)
    {
        puts("111");
        bzero(buf,50);
        recvfrom(udpsocket,buf,50,0,(struct sockaddr *)&raddr,&ret);
        printf("message recv from %s\n",buf);
    }

    close(udpsocket);
    return 0;

}