Examkin

Question

Difficulty: Very hardNetworking Ports and Protocols

A network security administrator is configuring access control rules on an internal perimeter firewall for a dedicated network telemetry server. The server requires encrypted command-line administrative access for system maintenance and must receive metric polling queries from remote management consoles using standard Simple Network Management Protocol (SNMP) polling. Which of the following port and transport layer protocol combinations must be permitted through the firewall to support these requirements? (Select TWO.)

  1. TCP port 22 for secure command-line administrationAnswer
  2. UDP port 161 for SNMP metric polling queriesAnswer
  3. C
    TCP port 161 for SNMP metric polling queries
  4. D
    UDP port 67 for internal hostname resolution

Answer

The firewall rules must permit TCP port 22 to allow secure SSH management access and UDP port 161 to support SNMP metric polling.
Encrypted command-line administration requires SSH, which uses connection-oriented TCP transport on port 22. Standard SNMP status polling requires connectionless UDP transport on port 161.

Step-by-Step Solution

1
Identify the required service for encrypted remote command-line access.
SSH (Secure Shell) is the industry standard protocol for encrypted command-line management.
SSH runs over TCP port 22 to guarantee reliable delivery of terminal commands.
2
Identify the required protocol and transport mechanism for SNMP metric polling.
SNMP agent polling queries use UDP port 161.
Network monitoring tools use unacknowledged UDP datagrams on port 161 to minimize network overhead during high-frequency status polling.
3
Evaluate the incorrect options for protocol or port role mismatches.
TCP port 161 incorrectly assigns TCP to standard SNMP polling, while UDP port 67 is a DHCP port misattributed to hostname resolution.
DNS handles hostname resolution using port 53, and standard SNMP polling operates over UDP rather than TCP.

Key Concept

Mapping network services to their exact transport layer protocols (TCP vs UDP) and default port numbers
Rate this question

Topics

Networking Ports and Protocols

More questions from this topic