NTP server X.X.X.X?

[JoshGarmonCiscoCCNA]

when configuring the NTP Client:

ntp server X.X.X.X

whose address is the X.X.X.X?

also, at least in Packet Tracer, there is this weird "key" part of the command that's not in any study material i'm reading...

ntp server X.X.X.X <key>

what is that?

Packet Tracer ALSO lacks the ntp master command so I don't know if ntp can even work.

[Julio E. Moisa]

Hi

Ntp server <ip address or domain name>  this command is used to sync the time with a public NTP server or a NTP server used to sync with a public server.

ntp server x.x.x.x key : is used when you are going to set up authentication with the ntp server. This link could be useful: http://www.packetu.com/2008/12/28/ntp-authentication-ciscos-implementation/

ntp master is used to configure the Cisco IOS software as a Network Time Protocol (NTP) master clock to which peers synchronize themselves when an external NTP source is not available. This link could be useful: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/bsm/command/bsm-cr-book/bsm-cr-n1.html#wp3294676008

Hope it is useful :-)

[JoshGarmonCiscoCCNA]

i'm still confused

i know about ntp trusted key and ntp authentication-key

but when would i need to configure the "key" after ntp server X.X.X.X?

[Julio E. Moisa · Accepted solution]

Hi Josh,

No worries, please let me share an example, we are going to configure 2 routers with NTP, R1 will be the ntp server and R2 ntp client. 

R1

ntp master 
ntp authentication-key 1 md5 HELLO   <-- configure authentication and it is assigned to one identifier, in few words key 1.

No we configure the client to sync the time using R1

R2

ntp authenticate
ntp authentication-key 1 md5 HELLO
ntp trust-key 1
ntp server 1.1.1.1 key 1

So R2 will be able authenticate with the NTP server only if it uses the same key id provided by R1 (NTP server), in this case key 1

Hope it is useful  :-)  

[JoshGarmonCiscoCCNA]

alright, good

i had to make sure i wasn't putting too many keys in