Output of ps command

Hi

Can you please tell me why the date in my ps command output line shows question marks ("?")

mqm 9254 404 0 Jan 24 ? 15:32 amqcrsta -m MQR_STUV
root 7508 1 0 Jan 10 ? 0:00 lp -d OP-5Si04
root 868 1 0 Jan 09 ? 0:10 tldcd
root 1014 1 3 04:29:45 ? 14:28 bpbkar -IEL -nfsok -dt 0 -ru root -nocont -no_security /usr/openv/netbackup/db
sper 21181 21135 0 03:10:16 pts/3 0:01 ssh aix5

Also, how can I see how long before has this process been started.

Thanks in advance
LS1429

Actually, to take your first line as an example, the start time is "Jan 24". That question mark is from the tty field. It means that the process in question does not have a controlling terminal. A process without a controling terminal is a daemon.

If you really need to know when on Jan 24 this process started, there may be a way. But that would depend on which version of unix that you are using.