How to synchronize cisco router or switch clock with Network Time Protocol (NTP)

When cisco IOS runs for first time or after reset default time and date needs to be set correct. You can to this manually or with synchronization. In this topic we will talk about synchronization with Network Time Protocol (NTP). for this you need first time choose NTP server and know it's IP address, you can find it here - https://tf.nist.gov/tf-cgi/servers.cgi
after this go to cisco terminal and enter following commands:
1. Cisco# configure terminal
2. Cisco(config)# ntp server <NTP server IP address>
after this you can verify how it works with commands:
Cisco# ntp status
Cisco# ntp associations
After every configuration change don't forger write config.