ervers. Servers are also clients, and can be peered with each other as well. Con- figuring an IOS device as an NTP client is the simpler of the two models, SO we'll start there. NTP Client To configure an IOS device to request accurate time from an NTP server, use the ntp server command. You can list as many NTP servers as you need, each on a separate line. Here, I've listed seven publicly available NTP servers. Using SO many will help illustrate how NTP behaves: ntp server 132.163.4.102 ntp server 193.67.79.202 ntp server 152.1.58.124 ntp server 128.118.46.3 ntp server 129.6.15.29 ntp server 64.236.96.53 ntp server 208.184.49.9 Once you've configured the NTP servers, you should begin receiving accurate time signals (assuming you can reach them). To see the statuses of the servers, and the time they are providing, use the command show ntp associations: 2950# sho ntp associations address ref clock reach delay offset +~132.163.4.102 ACTS. 109.0 ~193.67.79.202 282.7 81.38 ~152.1.58.124 0.0.0.0 16000. ~127.127.7.1 127.127.7.1 ~128.118.46.3 0.0.0.0 16000. -~129.6.15.29 .ACTS. -4.63 +~64.236.96.53 .ACTS. *~208.184.49.9 ACTS. * master (synced), # master (unsynced), + selected, - candidate, ~ configured A lot of information is presented, but you only need to know what some of it means. The address is, obviously, the server you configured. To the left of the address are one or more symbols indicating the status of the server. The key for these symbols appears in the last line of the output; Table 35-1 provides more detailed explana- tions. The line beginning with an asterisk (just above the key in this example) indicates the server with which the switch has synced its time. Chapter 35: Network Time Protocol Table 35-1. NTP association characters Character Description Synchronized to this peer Almost synchronized to this peer Peer selected for possible synchronization Peer is a candidate for selection Peer is statically configured The next column indicates the reference clock used for the listed server. This can be useful,