switch(config)# no sntp server 10.28.227.141
Operating with multiple SNTP server addresses
configured (Menu)
When you use the Menu interface to configure an SNTP server IP address, the new address writes over the
current primary address, if one is configured.
SNTP messages in the Event Log
If an SNTP time change of more than three seconds occurs, the switch's Event Log records the change. SNTP
time changes of less than three seconds do not appear in the Event Log.
Network Time Protocol (NTP)
All NTP communications use Coordinated Universal Time (UTC). An NTP server usually receives its time from an
authoritative time source, such as a radio clock or an atomic clock attached to a time server, and 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 each other.
NTP uses a stratum to describe the distance between a network device and an authoritative time source:
• A stratum 1 time server is directly attached to an authoritative time source (such as a radio or atomic clock or a
GPS time source).
• A stratum 2 NTP server receives its time through NTP from a stratum 1 time server.
Before synchronizing, NTP compares the time reported by several network devices and does not synchronize
with one that is significantly different, even if it is a stratum 1.
The security features of NTP can be used to avoid the accidental or malicious setting of incorrect time. One such
mechanism is available: an encrypted authentication mechanism.
Though similar, the NTP algorithm is more complex and accurate than the Simple Network Time Protocol (SNTP).
IMPORTANT: Enabling this feature results in synchronizing the system clock; therefore, it may affect
all sub-systems that rely on system time.
Commands
The following commands allow the user to configure NTP or show NTP configurations.
timesync Command
This command is used to configure the protocol used for network time synchronization.
Syntax
[no] timesync { timep | sntp | timep-or-sntp | ntp }
Options
no
Deletes all timesync configurations on the device.
timep
Updates the system clock using TIMEP.
Chapter 2 Time Protocols 39
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