Co On Last seen________ Last file backup
C1 No_ 2015-07-13 23:36 2015-07-18 14:22
C2 No_ 2015-07-14 07:09 2015-07-18 07:33
C3 Yes 2015-07-15 02:13 2015-07-20 02:47
The backup time can't be newer than the last seen time. Computers in the list randomly do or don't have an appropriate seen time. Whether the computer is online or offline seems to make no difference.