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Difficulty: EasyCommon Ports and Protocols

A network technician is configuring an internal server to automatically synchronize the system clocks of all managed switches and routers across the enterprise network. Which port and transport protocol combination must be permitted through internal firewalls to allow Network Time Protocol (NTP) traffic?

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

Answer

UDP port 123 is the standard port and protocol combination used by Network Time Protocol (NTP) to synchronize clock times across network infrastructure components.
Network Time Protocol (NTP) utilizes UDP port 123 to send and receive time synchronization messages across IP networks. UDP is utilized because time distribution requires low delay and low protocol overhead.

Step-by-Step Solution

1
Identify the required network service from the scenario
The scenario describes synchronizing system clocks across network devices, which is handled by Network Time Protocol (NTP).
Recognizing service function is necessary to determine the corresponding standard port.
2
Determine the transport layer protocol and default port assigned to NTP
NTP operates over UDP on port 123.
UDP is chosen for time synchronization due to its lower delay and lack of handshake overhead, operating over registered port 123.

Key Concept

Network Time Protocol (NTP) Port and Transport Assignment
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Topics

Common Ports and Protocols

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