ISC2 CC Network Security Practice Question
Which three ports are commonly used by secure protocols? (Choose THREE.)
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
✓
443 (HTTPS)
HTTPS uses 443, SSH uses 22, and LDAPS uses 636. HTTP (80), Telnet (23), and FTP (21) are insecure or unencrypted.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
80 (HTTP)
Why it's wrong here
Port 80 carries unencrypted HTTP, so it is not a secure protocol port. It is tempting because HTTP is ubiquitous for web traffic, yet confidentiality requires TLS, which runs on port 443; the secure-protocol answers are 443, 22 and 993 rather than the cleartext web port.
- ✓
443 (HTTPS)
Why this is correct
Port 443 carries HTTPS, which wraps HTTP inside TLS, encrypting credentials and session data in transit. This directly satisfies the stem's requirement for a secure protocol port, unlike cleartext alternatives such as port 80. Microsoft Entra ID authentication traffic and most modern web APIs rely on 443 for this reason.
- ✓
22 (SSH)
Why this is correct
Port 22 carries SSH, which encrypts the entire session including authentication credentials, satisfying the requirement for a secure protocol. Unlike Telnet on port 23, which transmits data in cleartext, SSH provides confidentiality and integrity, making it a standard choice for secure remote administration.
- ✗
23 (Telnet)
Why it's wrong here
Telnet on port 23 transmits credentials and session data in cleartext, so it is not secure. It is tempting because Telnet provides remote terminal access similar to SSH, but SSH on port 22 encrypts the session; Telnet's lack of encryption is precisely why it fails this secure-protocol requirement.
- ✓
636 (LDAPS)
Why this is correct
LDAPS wraps LDAP traffic in TLS on port 636, encrypting directory queries and bind operations so credentials and attribute data cannot be read in transit. This satisfies the stem's requirement for a secure protocol port, unlike plain LDAP on 389, which transmits credentials unencrypted.
Go deeper
Related to this question
Learn chapter
Secure Network Architecture and Design
Key term
Telnet
Telnet is a network protocol that provides a bidirectional, interactive text-based communication session between two machines over a network, typically used for remote access and management of network devices.
Key term
LDAPS
LDAPS encrypts LDAP traffic using SSL/TLS to secure directory queries and authentication over a network.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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