This tutorial is all about NTP Authentication configuration on cisco router.to perform this lab i have used cisco packet tracer Lab.To ensure that erroneous time information is not propagated throughout the network, NTP authentication can be configured.

Step 1:First Design the Topology diagram and assign IP Addreses.

assign ip address on router interface and server as i have mentioned in Topology diagram.And wait till all port show green signal.

Step 2: Configure Both NTP Server with key 1 and password is redhat.

Step 3:Now configure Router D as NTP Client of Both NTP Server.

 

D(config)#clock timezone CST -6

D(config)#ntp server 10.0.0.1

D(config)#ntp server 10.0.0.5

 

STEP 4:Now  configure NTP authentication on RouterD:

 

D(config)#ntp authentication-key 1 md5 redhat

D(config)#ntp trusted-key 1

D(config)#ntp server 10.0.0.1  key  1

 

Note that authentication-key must be same on the both NTP Devices.

 

Step 5:Verify NTP to see current date and time.

 

D#show clock

9:25:43.712 CST Sun Oct 29 2017

Step 6:Check the status of NTP synchronization.

 

D#show ntp status

Clock is synchronized, stratum 2, reference is 10.0.0.1

nominal freq is 250.0000 Hz, actual freq is 249.9990 Hz, precision is 2**19

reference time is DD76414A.000000D7 (15:24:58.215 UTC Sun Oct 29 2017)

clock offset is 0.00 msec, root delay is 0.00 msec

root dispersion is 0.02 msec, peer dispersion is 0.02 msec.