unknown messages on ssl server

[nymus]

Hi

I've a ssl webserver and I check the avalability of this machine
with a managment tools. The ssl service run 24 hours a day...

But I've seen on my management machine this message:
...
<date> 01:38 server <servername> <port-nr.> SVCDOWN at 01:38
<date> 01:39 server <servername> <port-nr.> SVCUP at 01:39
...
an that all 30 minutes!

What could be that? How can I to know from where come this messages
and to know what is it?
I think that could be in the configuration or other some processes
that make this things happen. I don't understand because this appears
every 30 min. and every days.

Have someone any ideas about that?

Regards,
nymus