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Difficulty: MediumCommon Ports and Protocols

Match each network protocol or service requirement on the left with its standard default port number and primary transport protocol on the right.

  • Simple Network Management Protocol (SNMP) polling queriesUDP port 161
  • Domain Name System (DNS) zone transfers between primary and secondary serversTCP port 22
  • Network Time Protocol (NTP) clock synchronizationUDP port 123

Answer

Simple Network Management Protocol (SNMP) polling queries matches UDP port 161; Secure File Transfer Protocol (SFTP) administrative file transfers matches TCP port 22; Domain Name System (DNS) zone transfers between primary and secondary servers matches TCP port 53; Network Time Protocol (NTP) clock synchronization matches UDP port 123.
Each service is correctly paired with its transport protocol and port: SNMP polling query traffic uses UDP port 161; SFTP leverages SSH encapsulation on TCP port 22; DNS zone transfers switch to TCP port 53 for reliability; and NTP time synchronization operates over UDP port 123.

Step-by-Step Solution

1
Identify the transport protocol and port requirements for management and polling services.
SNMP queries use UDP port 161 (SNMP traps use UDP 162).
Management polling relies on lightweight UDP communications.
2
Identify encrypted administrative file transfer protocols.
SFTP operates inside an SSH session on TCP port 22.
Unlike legacy FTP (TCP 20/21) or FTPS (TCP 989/990), SFTP shares SSH's underlying port.
3
Differentiate standard DNS queries from DNS zone transfers.
DNS zone transfers require reliable bulk data transfer over TCP port 53.
Standard client queries use UDP port 53, but large database transfers between DNS servers require TCP port 53.
4
Identify network synchronization protocol ports.
NTP utilizes UDP port 123.
Time synchronization relies on low-latency UDP packet delivery.

Key Concept

Common Network Ports and Transport Layer Dependencies
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Topics

Common Ports and Protocols

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