A NTP network usually gets its time from an authoritative time source, such as a radio clock or an atomic clock attached to a time server. NTP then distributes this time across the network. NTP is extremely efficient. No more than one packet per minute is necessary to synchronize two devices to within a millisecond of one another.

Before trying to configure NTP check for the ping test with NTP server.If NTP doesnt work upgrade the IOS to 12.3 (4)JA and use SNTP.

Note: Starting Cisco IOS® Software Release 12.3(4)JA, APs and bridges support SNTP instead of NTP. For more information, refer to the SNTP Replaces NTP section of Release Notes for Cisco Aironet Access Points, Cisco IOS Release 12.3(4)JA.

To configure the AP with the Command Line Interface (CLI) for Network Time Protocol (NTP), refer to the Understanding Simple Network Time Protocol section of Administering the Access Point

Simple Network Time Protocol (SNTP) is a simplified, client-only version of NTP. SNTP can only receive the time from NTP servers; it cannot be used to provide time services to other systems. SNTP typically provides time within 100 milliseconds of the accurate time, but it does not provide the complex filtering and statistical mechanisms of NTP.

For Simple Network Time Protocol (SNTP), refer to the Configuring SNTP section of Administering the Access Point.

To configure the AP with VxWorks for SNTP, refer to the Time Server Setup Page section of the Cisco Aironet 1200 Series Access Point Software Configuration Guide for VxWorks.

Note:An access point running 12.3(4)JA, when configured with "sntp broadcast client", will ignore NTP broadcasts from a v4 server.  If that server is reconfigured to report itself as v3, the
SNTP client will synchronize with no difficulty. So you need to do the following.

1. Configure the sntp client as a unicast client
(sntp server )

2. Reconfigure the NTP server as v3 rather than v4