Examkin

Question

Difficulty: EasyCommon Ports and Protocols

A network administrator needs to ensure that core infrastructure switches can automatically synchronize their system clocks with a centralized time server on the network. Which default port and transport protocol combination must be permitted through internal firewalls to allow Network Time Protocol (NTP) synchronization?

  1. UDP port 123Answer
  2. B
    TCP port 123
  3. C
    UDP port 161
  4. D
    TCP port 514

Answer

UDP port 123 is the standard port and transport protocol utilized by Network Time Protocol (NTP).
Network Time Protocol (NTP) uses UDP port 123 to provide clock synchronization across network-connected hardware. UDP is utilized because connection establishment overhead and TCP retransmissions would introduce latency variations that degrade timekeeping accuracy.

Step-by-Step Solution

1
Identify the required network service
The network service requested is Network Time Protocol (NTP), which synchronizes device clocks across a IP network.
Accurate timestamps across devices are essential for logging and event correlation.
2
Determine the transport protocol and port number for NTP
NTP standardized operations run on User Datagram Protocol (UDP) on well-known port 123.
UDP is chosen for NTP to avoid connection-establishment delays and retransmission delays that could distort time synchronization math.

Key Concept

Standard Network Port Assignments (NTP)
Rate this question

Topics

Common Ports and Protocols

More questions from this topic