The answer is that Telnet traffic leaving GigabitEthernet0/2 is blocked. This is correct because the ACL direction outbound filtering applies the access-group to traffic exiting the interface, meaning the router evaluates packets as they leave GigabitEthernet0/2 against the BLOCK_TELNET rules. Since the deny statement targets TCP port 23, any Telnet session initiated from inside the network and routed out this interface is dropped, while the subsequent permit ip any any allows all other outbound traffic. On the ENCOR 350-401 exam, this concept tests your understanding of ACL placement and direction—a common trap is confusing inbound versus outbound filtering, especially when the ACL name suggests a protocol but the direction determines what traffic is inspected. Remember the memory tip: "Outbound filters what leaves, inbound filters what arrives."
CCNP ACLs and CoPP Practice Question
This 350-401 practice question tests your understanding of acls and copp. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Consider the following configuration:
ip access-list extended BLOCK_TELNET
deny tcp any any eq 23
permit ip any any
!
interface GigabitEthernet0/2
ip access-group BLOCK_TELNET out
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Telnet traffic leaving GigabitEthernet0/2 is blocked.
The ACL is applied outbound, so it filters traffic leaving the interface. Telnet (port 23) is denied, all other traffic permitted.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Telnet traffic entering GigabitEthernet0/2 is blocked.
Why it's wrong here
The ACL is applied outbound, so it filters outgoing traffic, not incoming.
✓
Telnet traffic leaving GigabitEthernet0/2 is blocked.
Why this is correct
The outbound ACL denies TCP port 23 (Telnet) on egress.
Related concept
Standard ACLs match source addresses.
✗
All outbound traffic is blocked.
Why it's wrong here
Only Telnet is denied; the permit ip any any allows all other traffic.
✗
The ACL is incorrectly applied; only named ACLs can be applied outbound.
Why it's wrong here
Named ACLs can be applied inbound or outbound; the configuration is valid.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 350-401 ACL questions on filtering logic and placement.
ACLs and CoPP — This question tests ACLs and CoPP — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Telnet traffic leaving GigabitEthernet0/2 is blocked. — The ACL is applied outbound, so it filters traffic leaving the interface. Telnet (port 23) is denied, all other traffic permitted.
What should I do if I get this 350-401 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 350-401 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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