Network Time Protocol (NTP)


NTP version 4 is compliant to RFC 2030 (Simple Network Time Protocol). It is available from AIX® 6.1.

The Network Time Protocol (NTP) is widely used to synchronize a computer to Internet time servers or other sources, such as a radio or satellite receiver or telephone modem service. It provides accuracies typically less than a millisecond on LANs and up to a few milliseconds on WANs. Typical NTP configurations utilize multiple redundant servers and diverse network paths in order to achieve high accuracy and reliability.

NTP time synchronization services are widely available in the public Internet. The public NTP subnet in early 2008 includes several thousand servers in most countries and on every continent of the globe, including Antarctica. These servers support a total population estimated at over 25 million computers in the global Internet.

The NTP subnet operates with a hierarchy of levels, where each level is assigned a number called the stratum. Stratum 1 (primary) servers at the lowest level are directly synchronized to national time services. Stratum 2 (secondary) servers at the next higher level are synchronize to stratum 1 servers, and so on. Normally, NTP clients and servers with a relatively small number of clients do not synchronize to public primary servers. There are several hundred public secondary servers operating at higher strata and are the preferred choice.

NTPv3 and NTPv4 binaries coexist on AIX.

Important: By default, AIX points to NTP version 3 binaries.

NTP binaries directory mapping on AIX:
NTPv4 Binaries /usr/sbin/ntp4 NTPv3 Bianries /usr/sbin/ntp3 Default Symbolic link to NTP version 3 binaries from /usr/sbin directory
ntpd4 xntpd /usr/sbin/xntpd-->/usr/sbin/ntp3/xntpd
ntpdate4 ntpdate /usr/sbin/ntpdate-->/usr/sbin/ntp3/ntpdate
ntpdc4 xntpdc /usr/sbin/ntpdc-->/usr/sbin/ntp3/xntpdc
ntpq4 ntpq /usr/sbin/ntpq-->/usr/sbin/ntp3/ntpq
ntp-keygen4 Not Available /usr/sbin/ntp-keygen-->/usr/sbin/ntp4/ntp-keygen4
ntptrace4 ntptrace /usr/sbin/ntptrace-->/usr/sbin/ntp3/ntptrace
sntp4 sntp /usr/sbin/sntp-->/usr/sbin/ntp3/sntp
Note: 1 ntp-keygen is a new binary file in NTP version 4, it is not present in NTP version 3. So, the symbolic link needs to be created under /usr/sbin d directory, pointing to ntp4 binary ( /usr/sbin/ntp4/ntp-keygen4). ntptrace file is a binary file in NTP version 3, but it is a perl script in NTP version 4.