This 200-301 practice question tests your understanding of network services and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: an ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets.. 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.
Which ACL statement permits only SSH from host 10.10.10.50 to server 192.168.1.10?
permit tcp host 10.10.10.50 host 192.168.1.10 eq 22
This matches the correct protocol, source, destination, and destination port.
permit udp host 10.10.10.50 host 192.168.1.10 eq 22
Why wrong: SSH uses TCP, not UDP.
permit tcp any host 192.168.1.10 eq 22
Why wrong: This is too broad because it allows any source.
permit ip host 10.10.10.50 host 192.168.1.10
Why wrong: This permits all IP traffic, not only SSH.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
permit tcp host 10.10.10.50 host 192.168.1.10 eq 22
SSH uses TCP destination port 22. The source is the single host 10.10.10.50 and the destination is the single host 192.168.1.10.
Key principle: An ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
permit tcp host 10.10.10.50 host 192.168.1.10 eq 22
Why this is correct
This matches the correct protocol, source, destination, and destination port.
Related concept
An ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets.
permit udp host 10.10.10.50 host 192.168.1.10 eq 22
permit tcp any host 192.168.1.10 eq 22
Why it's wrong here
This is too broad because it allows any source.
When this WOULD be correct
If the question asked for any TCP traffic to be permitted from any host to the server 192.168.1.10 on port 22, then option C would be correct as it meets that broader requirement.
permit ip host 10.10.10.50 host 192.168.1.10
Why it's wrong here
This permits all IP traffic, not only SSH.
When this WOULD be correct
This option would be correct in a scenario where the question asks for a general rule allowing any IP traffic from a specific host to a server, without restrictions on the protocol or port. For example, if the question required allowing all types of communication from host 10.10.10.50 to server 192.168.1.10.
Option-by-option analysis
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
Why this is correct
This matches the correct protocol, source, destination, and destination port.
Why this is wrong here
SSH operates over TCP, not UDP. Using UDP port 22 would permit a different protocol (e.g., some VPNs or custom applications) and would not match SSH traffic, which requires TCP for reliable, connection-oriented communication.
★ When this WOULD be the correct answer
This option would be correct in a scenario where the question asks for permitting UDP traffic on port 22 for a specific application that uses UDP for communication, such as a custom protocol that mimics SSH behavior over UDP.
Why candidates choose this
Students may confuse SSH with other services that use UDP, or they might mistakenly think that port 22 can be used with either TCP or UDP. The well-known port number is correct, but the protocol is wrong.
Why this is wrong here
This ACL permits SSH traffic from any source IP address, not just from host 10.10.10.50. The question specifically requires restricting the source to that single host, so this statement is too permissive and does not meet the requirement.
★ When this WOULD be the correct answer
If the question asked for any TCP traffic to be permitted from any host to the server 192.168.1.10 on port 22, then option C would be correct as it meets that broader requirement.
Why candidates choose this
A student might focus only on the destination and port, overlooking the source restriction. They may think that specifying 'any' is acceptable because the destination and port are correct, but the source must be limited.
Why this is wrong here
This ACL permits all IP traffic (any protocol) from the specified source to the destination, not just SSH. It would allow Telnet, HTTP, ICMP, and other protocols, which violates the requirement to permit only SSH.
★ When this WOULD be the correct answer
This option would be correct in a scenario where the question asks for a general rule allowing any IP traffic from a specific host to a server, without restrictions on the protocol or port. For example, if the question required allowing all types of communication from host 10.10.10.50 to server 192.168.1.10.
Why candidates choose this
Students might think that using 'ip' is a shortcut to permit all traffic for that host pair, but they forget that the question explicitly requires only SSH. The 'ip' keyword is protocol-agnostic and does not filter by port.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
A common exam trap is selecting an ACL statement that permits UDP traffic on port 22 or permits all IP traffic from the source host. Since SSH exclusively uses TCP on port 22, permitting UDP or all IP protocols can either block SSH access or allow unintended traffic. Another trap is using 'any' as the source, which opens access to all hosts instead of restricting it to the specific host 10.10.10.50. These mistakes lead to either overly permissive or overly restrictive ACLs, failing the security objective and the exam requirement.
Detailed technical explanation
Access Control Lists (ACLs) are fundamental security tools in Cisco networking that control traffic flow by permitting or denying packets based on defined criteria such as source IP, destination IP, protocol, and port numbers. In the context of securing SSH access, ACLs filter TCP traffic specifically on port 22, which is the standard port for SSH connections. This precise filtering ensures only authorized hosts can initiate secure remote management sessions to a server. The correct ACL statement "permit tcp host 10.10.10.50 host 192.168.1.10 eq 22" explicitly permits TCP traffic from a single source IP address (10.10.10.50) to a single destination IP address (192.168.1.10) on destination port 22. This specificity is crucial because SSH uses TCP as its transport protocol and listens on port 22 by default. The ACL syntax uses "host" to specify exact IP addresses, and "eq 22" to match the destination port, ensuring no other traffic types or ports are allowed. A common exam trap is confusing the protocol or port number, such as permitting UDP instead of TCP or allowing all IP traffic instead of restricting to SSH. Practically, this ACL enforces strict access control, preventing unauthorized hosts or protocols from reaching the server via SSH. Understanding how ACLs match traffic based on protocol and port is essential for both exam success and real-world network security implementation.
Key takeaway
An ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review an ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Network Services and Security — This question tests Network Services and Security — An ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets..
The correct answer is: permit tcp host 10.10.10.50 host 192.168.1.10 eq 22 — SSH uses TCP destination port 22. The source is the single host 10.10.10.50 and the destination is the single host 192.168.1.10.
Review an ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets., then practise related 200-301 questions on the same topic to reinforce the concept.
An ACL in Cisco devices filters traffic by matching source IP, destination IP, protocol, and port to permit or deny packets.
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Last reviewed: May 17, 2026
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