NTP (NETWORK TIME PROTOCOL)

SYNCS CLOCKS - BETEWEN DIFFERENT SYSTEMS that communicate over a packet switched variable-latency network. TCP.

NTP uses UDP 123.

it’s important to make sure we’re all using the same time. it syncs within milisecs.

Goes through strata

stratum 0 - atomic clock, gps etc.

stratum 1 is synced to stratum 0. can go down to stratum 14

improemnts are PTP percision time protocol used to sync clocks sub micro second. more accurate

NTS - network time security protocol 0 extennon of ntp that provides cryptographic seciurity .

Network Time Protocol (NTP)

Purpose

• Syncs clocks between systems on packet-switched, variable-latency networks.
• Ensures consistent timestamps for logs, authentication, security, and transactions.
• Accuracy: within milliseconds of UTC.

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Protocol Details

• UDP port 123 (not TCP).
• Operates in client-server or peer-to-peer mode.

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Stratum Levels

• Stratum 0 → Reference clock (atomic, GPS, radio).
• Stratum 1 → Directly connected to stratum 0.
• Stratum 2+ → Gets time from stratum 1, passes it down.
• Can go down to Stratum 15 (Stratum 16 = unsynchronized).

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Improvements

• PTP (Precision Time Protocol):
  • More accurate than NTP (sub-microsecond).
  • Used in high-performance networks (finance, telecom, data centers).

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Security

• NTS (Network Time Security):
  • Extension of NTP.
  • Adds cryptographic authentication to prevent spoofing or tampering.

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✅ Exam Must-Knows

• NTP port = UDP 123
• Why important? = Consistent time across systems (logging, Kerberos, SSL/TLS, forensic analysis)
• Stratum 0 = atomic/GPS, Stratum 1 = synced directly
• PTP = higher accuracy than NTP
• NTS = secure NTP with crypto authentication

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⚡Memory Trick:

Think “123 NTP” → UDP port 123 is the timekeeper for all.

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