By Greg Shipley
Suppose you enter your office one morning and discover that a hacker had spoofed the CEO's e-mail address the previous week and posted a few bogus messages on the corporate intranet. Determined to locate the culprit, you track down the time of the posting. The Web server pinpoints the event at 2:49 p.m., Friday. Searching your trusted proxy server logs, you note that the Web server's clock and the proxy's clock are off by a few minutes. It might not seem like a huge problem, until you realize the proxy server receives approximately 10 requests per second at peak hours. That's 600 requests per minute, and 1,200 to 1,800 over a few minutes affected by the time discrepancy. You soon realize that even a one-minute difference can create time-consuming problems, and what appeared to be a simple task now has the makings of an epic quest.
Accurate logging is just one of many time-critical applications in operation today. The complexity of modern networking environments makes accurate time-keeping more important. NetWare, NT, Unix and other operating systems offer various native time-syncing mechanisms but cross-platform incompatibilities make enterprisewide deployment of these services difficult. Fortunately, we have NTP (Network Time Protocol), a standards-based (RFC 1305) method of maintaining accurate synchronization across multiple platforms.
NTP has been implemented on NT (with the NT Server Resource Kit), NetWare 5 (version 3.x and 4.x require third-party add-ons), Unix and Cisco Systems' IOS (Internetwork Operating System). With a well-planned NTP implementation administrators can have routers, servers, workstations, clients and any other NTP-aware device synchronized and accurate to a few milliseconds.
Unlike NetWare's timesync protocol, which attempts to synchronize time based on the adjustment of system clocks to an agreed time, NTP synchronizes according to the actual time. NTP implementations attempt to calculate the correct time based on multiple sources, typically attached to atomic clocks, GPS (Global Positioning System) satellite receivers and radio clocks. We use a Datum TymeServe 2100 time server in one of our Real-World Labs® in San Mateo, Calif., keeping the network accurate to within one millisecond.
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