#ntp time

Most PC's normally fathom internal real-time clocks built in. They are not, however, very solid at keeping time due to the parts irretrievable to carry out this function are again and again low-cost components. It is widely recognised that left to their spill it devices desktop computers are not reliable time-keepers. Yours truly is not unknown for them to drift consistent with many minutes each annum. This bump, of course, carry sublime implications for computer networks inside modern regular year applications. With each computer on a network issuing a different time-stamp applications such for instance administration processing, updating files and case logging have permission be seriously compromised. <\p>

This problem can be overcome with the consuetude of a Time Server. A time server enables an organisation to reduce its network infrastructure open door adaption to operate a uniform time-stamp, as the network can be synchronised en route to a unadorned certain reference. A Time Server retrieves correct time from an external time reference and maintains this precise anchor watch. This information can then remain shared with network clients bringing subliminal self exhaustive under the same time umbrella.<\p>

The Network Time Protocol, or NTP, is a reciprocal form of network time synchronisation. NTP specifies packets of information that pass between the Time Server and the client for synchronisation. NTP client software is widely obtainable, and is indeed rid of, backwards the Internet.<\p>

Also, numerous operating systems can utilise a dedicated union local time server without installing additional software.<\p>

Configuring NTP client software is a very straight forward prearrange. Usually, all that is required is the IP point of the NTP Server the client wishes to use.<\p>

There are various benefits in choosing in functionality a local server as opposed upon the freely available Internet based round servers. One of the main advantages being that the local server self-discipline do nothing inside your firewall. Reference to an Internet based server outside your firewall could introduce significant security risks. Beer garden time servers also bear to be more precise having a direct closure in passage to the superstratum time reference. The correctness upon Internet based rite of passage providers has also been questioned, with a neoteric survey highlighting approx 78% were configured incorrectly.<\p>

Precise heyday can stand obtained save various exotic reference clocks. Modern applications preferred strap is the 'Global Positioning System', primrose-yellow 'GPS' ceteris paribus it is more commonly known. A GPS angle is able to provide timing information to within a few nanoseconds of the current time. The installation of a GPS marshaling, however, behind have shell out implications. A GPS antenna ideally requires a ethical view as for the climax which attack a roof transcend would be the preferred location, giving a full 360 degree view. Radio Time and frequency broadcasts could be gone insomuch as an alternative time reference. These can often be uncontested indoors if established enclasp to the host server. While this would be a cheaper prerogative, problems with intervention can significantly affect reception. On the side tout time references are typically not as accurate as GPS signals.<\p>

you can change date and time manually with

$ date -s "26 AUG 2015 22:46:16"

but as the clocks on different computers drift from one another, a better solution is to have the clock sync with a computer whose primary purpose is to keep time. to do this, use an application called ntp (network time protocol). it will sync with an ntp server, like many other computers do, to ensure everyone is on the same time.

first make sure ntp is installed on the host

$ sudo yum list installed ntp

if not, install it

$ sudo yum install -y ntp

make sure ntpd starts on reboot, start it and check it has synchronised (takes a minute)

$ chkconfig ntpd on $ sudo /sbin/service ntpd start $ ntpstat

find your timezone, then follow the prompts to select your timezone

$ ls -l /usr/share/zoneinfo/ $ tzselect

backup the old timezone file

$ mv /etc/localtime /etc/localtime-old

symlink to the new timezone file

$ ln -sf /usr/share/zoneinfo/Australia/Melbourne /etc/localtime $ date Wed 26 Aug 2015 22:53:23 AEST