Configuring Ntp; About Ntp - Cisco Nexus 9000 Series Configuration Manual

Configuring NTP

This chapter describes how to configure the Network Time Protocol (NTP) on Cisco NX-OS devices.
This chapter includes the following sections:
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About NTP

The Network Time Protocol (NTP) synchronizes the time of day among a set of distributed time servers and
clients so that you can correlate events when you receive system logs and other time-specific events from
multiple network devices. NTP uses the User Datagram Protocol (UDP) as its transport protocol. 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
• A stratum 2 NTP server receives its time through NTP from a stratum 1 time server.
About NTP, page 9
Licensing Requirements for NTP, page 11
Prerequisites for NTP, page 11
Guidelines and Limitations for NTP, page 11
Default Settings for NTP, page 12
Configuring NTP, page 12
Verifying the NTP Configuration, page 19
Configuration Examples for NTP, page 19
Additional References, page 21
clock or a GPS time source).
Cisco Nexus 9000 Series NX-OS System Management Configuration Guide, Release 6.x
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