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Difficulty: Very hardCommon Ports and Protocols

A network architect is designing stateless access control rules for a perimeter gateway to support an out-of-band network management architecture. The security design mandates four specific operational services:
1. Centralized device administration AAA that encrypts the entire packet payload.
2. Accurate network time synchronization across all infrastructure nodes.
3. Unsolicited, asynchronous alert notifications sent from managed edge switches to a central monitoring station.
4. Secure, encrypted transmission of system log messages to a centralized SIEM platform.

Which combination of protocols, transport layer types, and default port numbers correctly satisfies all four architecture requirements?

  1. TACACS+ on TCP port 49, NTP on UDP port 123, SNMP Traps on UDP port 162, and Syslog over TLS on TCP port 6514Answer
  2. B
    RADIUS on UDP port 1812, NTP on TCP port 123, SNMP Traps on UDP port 161, and Syslog over TLS on UDP port 514
  3. C
    TACACS+ on UDP port 49, NTP on UDP port 123, SNMP Traps on TCP port 162, and Syslog over TLS on TCP port 514
  4. D
    RADIUS on TCP port 49, NTP on UDP port 514, SNMP Traps on UDP port 161, and Syslog over TLS on TCP port 6514

Answer

TACACS+ on TCP port 49, NTP on UDP port 123, SNMP Traps on UDP port 162, and Syslog over TLS on TCP port 6514 correctly satisfies all four requirements.
The correct selection accurately pairs each specified service with its standard port and transport protocol: TACACS+ encrypts the entire payload over TCP port 49; NTP synchronizes time via UDP port 123; SNMP Traps deliver asynchronous notifications to UDP port 162; and Syslog over TLS secures system logs over TCP port 6514.

Step-by-Step Solution

1
Identify the protocol that encrypts the entire AAA packet payload and its transport parameters.
TACACS+ encrypts the complete packet body (unlike RADIUS, which encrypts only passwords) and operates over TCP port 49.
Security requirement 1 specifies full payload encryption for device administration AAA.
2
Determine the transport protocol and default port for Network Time Protocol (NTP).
NTP uses UDP port 123.
Requirement 2 mandates network time synchronization.
3
Differentiate between SNMP Polling and SNMP Trap transport definitions.
Asynchronous switch notifications (Traps) are sent to destination UDP port 162, whereas NMS polling requests target UDP port 161.
Requirement 3 specifies unsolicited, asynchronous alert notifications from managed switches.
4
Identify the secure transport variant for system log forwarding.
Standard unencrypted Syslog uses UDP port 514, while encrypted Syslog over TLS uses TCP port 6514.
Requirement 4 specifies encrypted transmission of log messages.

Key Concept

Core Management Ports and Transport Protocols
Estimated Time:2m 0s
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Topics

Common Ports and Protocols

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