| 2.4 |  | Router Management |
| 2.4.3 |  | Time |

| Accurate time is important for good network audit and management. There are several ways to provide network devices with the correct time, including the following:

- Network Time Protocol (NTP)
- GPS
- Two-Way Satellite
- Modem Time Service

The Network Time Protocol (NTP) provides a common time base for networked routers, servers, and other devices. A synchronized time system enables the correlation of the syslog and Cisco IOS debug outputs to specific events. For example, it is possible to find call records for specific users within one millisecond.

Comparing logs from various networks is essential for the following procedures:

- Troubleshooting
- Fault analysis
- Security incident tracking

Without precise time synchronization between all the various logging, management, and AAA functions, time comparisons are not possible. An NTP enabled network usually gets its time from an authoritative time source, such as a Cisco router configured as an NTP server, a radio clock, or an atomic clock attached to a timeserver . NTP then distributes this time across the network. NTP is extremely efficient . No more than one packet per minute is necessary to synchronize two machines to within a millisecond of one another. NTP runs over UDP, which in turn runs over IP.

For more details on configuring and verifying NTP see the Demonstration Activity below.

| Lab Activity Lab Exercise: Setting Time In this lab, the student will learn how to accomplish the following:

- Setting the time manually
- Configuring NTP
- Monitoring Time Services

| Media Activity Demonstration Activity: Configuring and verifying NTP In this activity, students will learn the steps to configure and verify NTP.

| Web Links http://tycho.usno.navy.mil/time.html http://www.eecis.udel.edu/~mills/ntp/servers.html http://www.beaglesoft.com http://www.trusted-time.com/syncserver_s100.asp

http://www.gpsclock.com/specs.html

http://www.absolutetime.com/products/products.htm

http://www.symmetricom.com/