ISC2 CC Network Security Practice Question
Which protocol is considered insecure because it transmits data, including credentials, in cleartext?
⚠ Common exam trap
Many exam-takers confuse similarly named protocols — candidates may pick SFTP or SSH assuming they are insecure because they sound like FTP, when in fact Telnet is the only cleartext option listed.
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
✓
Telnet
Telnet transmits all data, including usernames and passwords, in cleartext over the network, making it trivial to intercept with packet sniffing. It lacks encryption and is considered insecure for any authentication or sensitive data. This is why Telnet has been replaced by SSH for remote administration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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SFTP
Why it's wrong here
SFTP runs over SSH, encrypting all data and credentials in transit, so it does not transmit cleartext. It is tempting because it is a file-transfer protocol like FTP, and it would be correct when files must be moved securely between hosts across an untrusted network.
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SSH
Why it's wrong here
SSH encrypts the entire session, including authentication, so it does not transmit credentials in cleartext. It is the correct answer when a question asks which protocol secures remote shell access, replacing insecure cleartext alternatives such as Telnet or FTP.
- ✓
Telnet
Why this is correct
Telnet transmits all session data, including usernames and passwords, as unencrypted cleartext, so anyone capturing traffic on the network can read credentials directly. This satisfies the stem's constraint of a protocol insecure specifically because it sends credentials in cleartext, unlike SSH, which encrypts the entire session.
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HTTPS
Why it's wrong here
HTTPS encrypts traffic with TLS, so credentials are never sent in cleartext; it is the secure counterpart to HTTP. It is tempting because it is the standard web protocol, and it would be the right choice when a browser must reach a site securely over an untrusted network.
Go deeper
Related to this question
Learn chapter
Wireless and Remote Access Security
Key term
Encryption
Encryption is the process of converting readable data into a secret code to prevent unauthorized access.
Key term
SSH
SSH (Secure Shell) is a cryptographic network protocol that provides secure, encrypted communication and remote administration between two devices over an unsecured network.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This CC practice question is part of Courseiva's free ISC2 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 CC exam.