CPENT Iot And OT Exploitation Practice Question
An ethical hacker is examining an operational technology (OT) network and needs to identify programmable logic controllers (PLCs) using their native industrial protocols. Which default TCP port should the hacker scan to discover Modbus/TCP devices?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
TCP 502
Modbus/TCP is an open protocol widely used in SCADA environments and operates natively over TCP port 502.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
TCP 102
Why it's wrong here
Port 102 is typically used for ISO-TSAP / Siemens S7 communication protocols.
- ✗
TCP 20000
Why it's wrong here
Port 20000 is often used by DNP3, not Modbus/TCP.
- ✓
TCP 502
Why this is correct
Port 502 is the official registered TCP port for Modbus communications.
- ✗
UDP 44818
Why it's wrong here
Port 44818 is used for EtherNet/IP explicit messaging, not Modbus/TCP.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official EC-Council exam blueprint
This CPENT practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CPENT exam.