CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. 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.
Network Topology
You are connected to R1. The network currently permits all HTTP traffic from hosts on the 192.168.1.0/24 LAN to reach the web server at 203.0.113.10, but SSH traffic (TCP port 22) from the same LAN is being blocked. Additionally, you must ensure that no other traffic from the LAN reaches the server. Configure an extended ACL on R1 to allow only HTTP and SSH from the LAN to the server, and apply it inbound on the correct interface. Verify your solution.
R1#show running-config | section interface
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
ip access-group BLOCK_SSH in
duplex auto
speed auto
!
interface GigabitEthernet0/1
ip address 203.0.113.1 255.255.255.252
duplex auto
speed auto
!
R1#show access-lists
Extended IP access list BLOCK_SSH
10 deny tcp 192.168.1.0 0.0.0.255 host 203.0.113.10 eq 22
20 permit ip any any
A
Remove the existing ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/0.
This is correct because the existing ACL BLOCK_SSH denies SSH but permits all other traffic, which does not meet the requirement to block everything except HTTP and SSH. By removing and deleting the old ACL, creating a new ACL that explicitly permits only HTTP and SSH, and applying it inbound on the LAN-facing interface, the implicit deny at the end of the ACL will block all other traffic from the LAN to the server.
B
Modify the existing ACL BLOCK_SSH by adding a permit statement for HTTP and changing the deny SSH to permit SSH, then reapply it inbound on GigabitEthernet0/0.
Why wrong: This is incorrect because the existing ACL BLOCK_SSH has a permit ip any any statement at the end, which would still allow all other traffic. Simply modifying the deny SSH to permit SSH and adding a permit HTTP would not remove the permit ip any any, so all traffic would still be permitted.
C
Create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/1 (the WAN interface).
Why wrong: This is incorrect because the ACL should be applied inbound on the interface closest to the source of the traffic, which is GigabitEthernet0/0 (the LAN interface). Applying it inbound on the WAN interface would not filter traffic as it enters the router from the LAN; it would only filter traffic coming from the WAN.
D
Create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it outbound on GigabitEthernet0/0.
Why wrong: This is incorrect because the ACL should be applied inbound on the LAN interface to filter traffic as it enters the router. Applying it outbound on the same interface would filter traffic leaving the router towards the LAN, which is not the direction of the traffic flow from LAN to server.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove the existing ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/0.
The existing ACL BLOCK_SSH is applied inbound on GigabitEthernet0/0 and explicitly denies SSH from the LAN to the server, but permits all other IP traffic (including HTTP). The requirement is to allow only HTTP and SSH, blocking everything else. The solution is to remove the current ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from the LAN to the server for ports 80 (HTTP) and 22 (SSH), and implicitly deny all other traffic, then reapply it inbound on GigabitEthernet0/0.
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.
✓
Remove the existing ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/0.
Why this is correct
This is correct because the existing ACL BLOCK_SSH denies SSH but permits all other traffic, which does not meet the requirement to block everything except HTTP and SSH. By removing and deleting the old ACL, creating a new ACL that explicitly permits only HTTP and SSH, and applying it inbound on the LAN-facing interface, the implicit deny at the end of the ACL will block all other traffic from the LAN to the server.
Related concept
Standard ACLs match source addresses.
✗
Modify the existing ACL BLOCK_SSH by adding a permit statement for HTTP and changing the deny SSH to permit SSH, then reapply it inbound on GigabitEthernet0/0.
Why it's wrong here
This is incorrect because the existing ACL BLOCK_SSH has a permit ip any any statement at the end, which would still allow all other traffic. Simply modifying the deny SSH to permit SSH and adding a permit HTTP would not remove the permit ip any any, so all traffic would still be permitted.
✗
Create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/1 (the WAN interface).
Why it's wrong here
This is incorrect because the ACL should be applied inbound on the interface closest to the source of the traffic, which is GigabitEthernet0/0 (the LAN interface). Applying it inbound on the WAN interface would not filter traffic as it enters the router from the LAN; it would only filter traffic coming from the WAN.
✗
Create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it outbound on GigabitEthernet0/0.
Why it's wrong here
This is incorrect because the ACL should be applied inbound on the LAN interface to filter traffic as it enters the router. Applying it outbound on the same interface would filter traffic leaving the router towards the LAN, which is not the direction of the traffic flow from LAN to server.
Option-by-option analysis
Why each answer is right or wrong
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.
✓Remove the existing ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/0.Correct answer▾
Why this is correct
This is correct because the existing ACL BLOCK_SSH denies SSH but permits all other traffic, which does not meet the requirement to block everything except HTTP and SSH. By removing and deleting the old ACL, creating a new ACL that explicitly permits only HTTP and SSH, and applying it inbound on the LAN-facing interface, the implicit deny at the end of the ACL will block all other traffic from the LAN to the server.
✗Modify the existing ACL BLOCK_SSH by adding a permit statement for HTTP and changing the deny SSH to permit SSH, then reapply it inbound on GigabitEthernet0/0.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the existing ACL contains a permit ip any any statement that would override any specific denies, allowing all traffic.
Why candidates choose this
Candidates pick this because they think they can edit the existing ACL without considering the existing permit ip any any statement, and they want to avoid deleting and recreating the ACL.
✗Create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/1 (the WAN interface).Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that ACLs should be applied inbound on the interface where the traffic enters the router, not on the outbound interface towards the destination.
Why candidates choose this
Candidates pick this because they mistakenly think the ACL should be applied on the interface facing the server to filter traffic going out, but inbound ACLs are more efficient and standard practice.
✗Create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it outbound on GigabitEthernet0/0.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that outbound ACLs filter traffic exiting the interface, but the traffic from LAN to server enters the router via GigabitEthernet0/0 and exits via another interface (e.g., WAN). An outbound ACL on GigabitEthernet0/0 would not affect traffic going to the server.
Why candidates choose this
Candidates pick this because they confuse inbound and outbound ACL application, thinking that outbound on the LAN interface will filter traffic leaving the LAN, but the traffic is actually entering the router from the LAN.
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
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
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 200-301 ACL questions on filtering logic and placement.
Network Services and Security — This question tests Network Services and Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Remove the existing ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from 192.168.1.0/24 to host 203.0.113.10 for ports 80 and 22, and apply it inbound on GigabitEthernet0/0. — The existing ACL BLOCK_SSH is applied inbound on GigabitEthernet0/0 and explicitly denies SSH from the LAN to the server, but permits all other IP traffic (including HTTP). The requirement is to allow only HTTP and SSH, blocking everything else. The solution is to remove the current ACL from the interface, delete the ACL, create a new extended ACL that permits tcp from the LAN to the server for ports 80 (HTTP) and 22 (SSH), and implicitly deny all other traffic, then reapply it inbound on GigabitEthernet0/0.
What should I do if I get this 200-301 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 200-301 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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