Until_Log_File  and  Until_Log_Pos  indicate the log file name and position that define the coordinates at which the replication SQL thread stops executing. For more information on  UNTIL  clauses, see Section 13.4.2.8, “START SLAVE | REPLICA Statement” . These fields show the SSL parameters used by the replica to connect to the source, if any. Source_SSL_Allowed  has these values: The values of the other SSL-related fields correspond to the values of the  SOURCE_SSL_*  options of the CHANGE REPLICATION SOURCE TO  statement (from MySQL 8.0.23), or the  MASTER_SSL_*  options of the  CHANGE MASTER TO  statement (before MySQL 8.0.23). See Section 13.4.2.1, “CHANGE MASTER TO Statement” . This field is an indication of how “late”  the replica is: In essence, this field measures the time difference in seconds between the replication SQL thread and the replication I/O thread. If the network connection between source and replica is fast, the replication I/O thread is very close to the source, so this field is a good approximation of how late the replication SQL thread is compared to the source. If the network is slow, this is  not  a good approximation; the replication SQL thread may quite often be caught up with the slow-reading replication I/O thread, so Seconds_Behind_Source  often shows a value of 0, even if the replication I/O thread is late compared to the source. In other words,  this column is useful only for fast networks . This time difference computation works even if the source and replica do not have identical clock times, provided that the difference, computed when the replica I/O thread starts, remains constant from then on. Any changes, including NTP updates, can lead to clock skews that can make calculation of Seconds_Behind_Source  less reliable. In MySQL 8.0, this field is  NULL  (undefined or unknown) if the replication SQL thread is not running, or if the SQL thread has consumed all of the relay log and the replication I/O thread is not running. (In older versions of MySQL, this field was  NULL  if the replication SQL thread or the replication I/O thread was not running or was not connected to the source.) If the replication I/O thread is running but the relay log is exhausted,  Seconds_Behind_Source  is set to 0. The value of  Seconds_Behind_Source  is based on the timestamps stored in events, which are preserved through replication. This means that if a source M1 is itself a replica of M0, any event from M1’s binary log that originates from M0’s binary log has M0’s timestamp for that event. This enables 2953 SHOW Statements • Source_SSL_Allowed ,  Source_SSL_CA_File ,  Source_SSL_CA_Path ,  Source_SSL_Cert , Source_SSL_Cipher ,  Source_SSL_CRL_File ,  Source_SSL_CRL_Path ,  Source_SSL_Key , Source_SSL_Verify_Server_Cert • Yes  if an SSL connection to the source is permitted. • No  if an SSL connection to the source is not permitted. • Ignored  if an SSL connection is permitted but the replica server does not have SSL support enabled. • Seconds_Behind_Source •When the replica is actively processing updates, this field shows the difference between the current timestamp on the replica and the original timestamp logged on the source for the event currently being processed on the replica. •When no event is currently being processed on the replica, this value is 0.