As if network administrators don’t have enough to worry about, keeping their timing right is a big priority. Not timing of the work they do, but network timing of the type done by NTP (network time protocol) servers with master clocks.
This is about to become important because a leap second has to be added to their systems on Dec. 31 — at precisely 6:59:59 p.m. Eastern Standard Time. So admins have to start thinking about how it will affect their servers, routers, switches and operating systems. They have a guide — the last time it had to be done was just over a year ago, June 30, 2015.
Just like in a leap year when a day is added to the calendar, a leap second has to be added periodically to precision equipment bring atomic time in line with the Earth’s actual rotation (also called astronomical time). Among those who need precision time are financial trading companies, telecommunications providers and airlines.
This will be the 27th time since 1972 a second has been added to world clocks.
Most of the time equipment makers ensure their gear is able to to it right, but sometimes there are foul-ups.  The June 30, 2012 leap second resulted in unexpected computer system outages and crashes, including the Amadeus airline management system, LinkedIn, Foursquare, Yelp, and Opera and some Internet service providers. According to one Cisco Systems blog, an Australian service provider has reported that a large number of its Ethernet switches seized up over a two-hour period following the leap second. However, the change was largely well managed that year and in 2015.
Hopefully by now the industry has ironed out ways to make this periodic time shift painless, but one of them is to make sure that administrators today — a little over two months ahead of the event — are prepared.
One of the first IT companies to remind administrators is Cisco, which last week published an information page on the matter that includes information on all products. It also promises updates will be released this month for its products to prepare for the evnt.
The vendor also warns that to make the change as painless as possible administrators should ensure NTP sources and strate are properly deployed, all version of  NTP  are consistent across the network and common time-driven alarms are properly managed.
“For most companies it’s not a big deal,” industry analyst Zeus Kerravala said in an interview Monday. “But if you’re dealing with high frequency trading and real-time data monitoring it could matter. Just make sure any operating system you’re running on your network devices supports the latest version of network time protocol to pick up the leap second change.”
