NDB Cluster Configuration Files The API nodes for which no host names are set use the TCP transporter to communicate with data nodes independent of the hosts on which they are started; the parameters and values set in the  [tcp default] section of the configuration file apply to all TCP transporters in the cluster. For optimum performance, you can define a spin time for the SHM transporter ( ShmSpinTime  parameter); this affects both the data node receiver thread and the poll owner (receive thread or user thread) in  NDB . • Checksum Version (or later) NDB 8.0.13 Type or units boolean Default true Range true, false Restart Type N (NDB 8.0.13) This parameter is a boolean ( Y / N ) parameter which is disabled by default. When it is enabled, checksums for all messages are calculated before being placed in the send buffer. This feature prevents messages from being corrupted while waiting in the send buffer. It also serves as a check against data being corrupted during transport. • Group Version (or later) NDB 8.0.13 Type or units unsigned Default 35 Range 0 - 200 Restart Type N (NDB 8.0.13) Determines the group proximity; a smaller value is interpreted as being closer. The default value is sufficient for most conditions. • HostName1 • HostName2 4228 Version (or later) NDB 8.0.13 Type or units name or IP address Default [...] Version (or later) NDB 8.0.13 Type or units name or IP address Default [...] Range ... Restart Type N (NDB 8.0.13) The  HostName1  and  HostName2  parameters can be used to specify specific network interfaces to be used for a given SHM connection between two nodes. The values used for these parameters can be host names or IP addresses.