What is Refid in NTP?
Abstract. NTP’s Reference ID, or REFID, identifies the source of time in a timestamp or time packet. In NTP packets sent over the network the REFID is used to identify the “system peer”, and in the long-term general case its fundamental purpose is to prevent a one-degree timing loop.
What is a NTP?
Network Time Protocol (NTP) is a protocol that allows the synchronization of system clocks (from desktops to servers). Having synchronized clocks is not only convenient but required for many distributed applications. Therefore the firewall policy must allow the NTP service if the time comes from an external server.
What is the difference between NTP and SNTP?
NTP has complex synchronisation algorithms that calibrate the system clock to match the frequency of an accurate reference clock. SNTP is a simplified sub-set of the algorithms used by the NTP protocol. SNTP steps the host computers system time rather than slowly slewing it towards the correct time.
What is NTP offset delay?
Offset is generally measured in milliseconds. Delay: Delay in a NTP server describes the round-trip delay or latency of a timing message passed from client to server and back again. The delay is important so that network delays can be calculated and accounted for by a time client.
Why is NTP important for security?
The use of authentication mechanisms in Network Time Protocol (NTP) is important to prevent the manipulation of time information by an attacker. The Symmetric Key based method and the Autokey approach are such mechanisms that have been around for many years.
Is SNTP compatible with NTP?
The NTP and SNTP protocols are completely interoperable. Any SNTP client can synchronize to any NTP server. This is primarily because the packets of information exchanged are identical.
Why is PTP better than NTP?
better. PTP was designed for local networks with broadcast/multicast transmission and, in ideal conditions, the system clock can be synchronized with sub-microsecond accuracy to the reference time….Summary.
| NTP | PTP | |
|---|---|---|
| Multiple sources | Yes | No |
| Estimation of maximum error | Yes | No |
| Authentication | Yes | Experimental |