Quick Answer
The answer is SSL/TLS (OpenVPN) because it delivers the best confidentiality and integrity for remote access while using a single UDP port, typically port 1194. This protocol wraps traffic in TLS encryption, such as AES-256-GCM, and adds HMAC authentication, ensuring data remains private and unaltered as it traverses the internet. On the ISC2 Certified in Cybersecurity CC exam, this question tests your understanding of how VPN protocols handle firewall traversal and port simplicity—a common trap is choosing IPsec, which often requires multiple ports or protocols like ESP and IKE, making it less ideal for teleworkers behind restrictive NAT. Remember that SSL/TLS operates at the transport layer, so it behaves like HTTPS traffic, easily slipping through firewalls that block other protocols. A quick memory tip: think “Single UDP, Strong SSL” to recall that OpenVPN uses one UDP port and TLS for robust security, making it the go-to for simple, secure remote access.
This CC practice question tests your understanding of network security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network administrator needs to allow secure remote access for teleworkers. Which VPN protocol provides the best confidentiality and integrity while using a single UDP port?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
PPTP
Why wrong: PPTP uses TCP port 1723 and has known security vulnerabilities.
SSL/TLS (OpenVPN)
OpenVPN uses a single UDP port and provides strong encryption.
L2TP/IPsec
Why wrong: L2TP/IPsec uses multiple UDP ports (500, 4500, 1701) and is complex.
IKEv2
Why wrong: IKEv2 uses UDP ports 500 and 4500.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
SSL/TLS (OpenVPN)
SSL/TLS (OpenVPN) is correct because it provides robust confidentiality and integrity through TLS encryption (e.g., AES-256-GCM) and HMAC authentication, while operating over a single UDP port (typically 1194). This makes it ideal for teleworkers as it can traverse NAT and firewalls easily, unlike protocols that require multiple ports or IPsec's complex port/protocol handling.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
PPTP
Why it's wrong here
PPTP uses TCP port 1723 and has known security vulnerabilities.
SSL/TLS (OpenVPN)
Why this is correct
OpenVPN uses a single UDP port and provides strong encryption.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
L2TP/IPsec
IKEv2
Why it's wrong here
IKEv2 uses UDP ports 500 and 4500.
Common exam traps
ISC2 often tests the misconception that L2TP/IPsec is the best for secure remote access because it is commonly used in site-to-site VPNs, but the key constraint here is 'single UDP port,' which eliminates L2TP/IPsec and IKEv2, and PPTP is insecure.
Detailed technical explanation
OpenVPN uses a TLS handshake to establish a secure control channel, then derives session keys for the data channel, which can use AES-GCM for authenticated encryption (confidentiality + integrity). It encapsulates all traffic in UDP datagrams on a single port (default 1194), making it highly NAT-friendly; in contrast, IPsec-based solutions often require additional configuration for NAT traversal and may fail in restrictive environments. A real-world scenario is a teleworker behind a strict hotel firewall that only allows UDP 1194, where OpenVPN works seamlessly while L2TP/IPsec or IKEv2 would be blocked.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
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FAQ
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
The correct answer is: SSL/TLS (OpenVPN) — SSL/TLS (OpenVPN) is correct because it provides robust confidentiality and integrity through TLS encryption (e.g., AES-256-GCM) and HMAC authentication, while operating over a single UDP port (typically 1194). This makes it ideal for teleworkers as it can traverse NAT and firewalls easily, unlike protocols that require multiple ports or IPsec's complex port/protocol handling.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network administrator needs to provide secure remote access to internal resources for employees working from home. The solution must encrypt all traffic and authenticate users before granting access. Which protocol should be used?
easyWhy C: C is correct because SSL/TLS VPNs (e.g., Cisco AnyConnect) provide encrypted tunnels over HTTPS (port 443) and support user authentication via certificates, RADIUS, or LDAP. This allows secure remote access to internal resources without requiring a persistent IPsec tunnel, making it ideal for home workers with dynamic IPs.
Variation 2. A company wants to allow remote employees to securely access internal resources over the internet. Which technology is most appropriate?
easyWhy D: A VPN (Virtual Private Network) creates an encrypted tunnel over the internet, typically using protocols like IPsec or TLS, to securely connect remote users to internal resources. This ensures confidentiality, integrity, and authentication of data in transit, making it the standard solution for remote access security.
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Last reviewed: Jun 30, 2026
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