static InetAddress _getDefaultMcastAddress() {
    // Default MCast address can be just IPv4 address.
    // On IPv6 machines, JGroups converts IPv4 address to equivalent IPv6 address.
    try {
      String ipLiteral = MembershipConfig.DEFAULT_MCAST_ADDRESS;
      return InetAddress.getByName(ipLiteral);
    } catch (UnknownHostException ex) {
      // this should never happen
      throw new Error(
          String.format("Unexpected problem getting inetAddress: %s",
              ex),
          ex);
    }
  }
The default value of the {@link ConfigurationProperties#MCAST_ADDRESS} property. Current value
is <code>239.192.81.1</code>
geode-core/src/main/java/org/apache/geode/distributed/internal/DistributionConfig.java