Server time synchronization
Web services in the cloud a very time sensitive. Because of that, services will not work or run if the call is made with a time not in the current time frame. Server clock needs to be fixed every when and then. The sympthom your clock is not current, is an error message like this:
Request timestamp: Wed, 27 Mar 2013 19:33:12 GMT expired. It must be within 300 secs/ of server time.
To make sure the clock on your server is current, a weekly cron job is perfect:
#----------------------------------------------- #Min Hour Day Month Weekday Command #----------------------------------------------- 25 1 * * 0 /usr/sbin/ntpdate ntp.ubuntu.com pool.ntp.org
IMHO it’s quicker and better than other solutions, that involve to run a deamon or install a new package.