The correct solution is to remove the existing ACL and replace it with an extended ACL that permits only TCP port 443 from source 192.0.2.0/24 to destination 203.0.113.0/24, applied inbound on G0/1. This works because an ACL with a single deny ip any any entry blocks all traffic, including HTTPS; by creating a permit statement for the specific traffic and relying on the implicit deny any at the end, only HTTPS is allowed while everything else is denied. On the CCNA 200-301 v2 exam, this tests your understanding of extended ACL syntax, the implicit deny rule, and the importance of ACL order—a common trap is forgetting to remove the old ACL before applying the new one, or misplacing the eq 443 operator. Remember the mnemonic: "Permit the port, deny the rest—implicit deny does the rest."
CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 administrator wants to permit only HTTPS traffic (TCP port 443) from the 192.0.2.0/24 network to the 203.0.113.0/24 network, while denying all other IP traffic. Currently, an ACL applied inbound on G0/1 is blocking all traffic, including HTTPS. Identify the issue and correct the ACL configuration so that only HTTPS traffic is permitted.
R1# show running-config | section interface GigabitEthernet0/1
interface GigabitEthernet0/1
ip address 192.0.2.1 255.255.255.0
ip access-group BLOCK_IN in
duplex auto
speed auto
R1# show access-lists
Extended IP access list BLOCK_IN
10 deny ip any any
R1# show ip interface GigabitEthernet0/1 | include access
Inbound access list is BLOCK_IN
A
Remove the existing ACL, then create an extended ACL with a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443, and apply it inbound on G0/1.
This is correct because it removes the overly restrictive deny ip any any entry and replaces it with a permit statement that matches only HTTPS traffic from the specified source to destination. The implicit deny at the end of the ACL then blocks all other traffic, achieving the desired policy.
B
Add a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443 before the existing deny ip any any entry in the ACL.
Why wrong: This is incorrect because ACLs process entries in order, and the deny ip any any entry will still match and block all traffic, including HTTPS, before the permit statement is evaluated.
C
Remove the existing ACL and create a standard ACL with permit 192.0.2.0 0.0.0.255, then apply it inbound on G0/1.
Why wrong: This is incorrect because standard ACLs can only match source IP addresses, not destination IP addresses or port numbers. They cannot filter based on TCP port 443, so they would permit all traffic from the source network, not just HTTPS.
D
Remove the existing ACL and create an extended ACL with a permit statement for tcp any any eq 443, then apply it inbound on G0/1.
Why wrong: This is incorrect because it permits HTTPS traffic from any source to any destination, which violates the requirement to restrict traffic only from 192.0.2.0/24 to 203.0.113.0/24.
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, then create an extended ACL with a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443, and apply it inbound on G0/1.
The ACL BLOCK_IN currently has a single deny ip any any entry, which blocks all traffic inbound on G0/1. The correct solution is to first remove the existing ACL, then create a new extended ACL that permits TCP 443 from source network 192.0.2.0/24 to destination network 203.0.113.0/24, and apply it inbound on G0/1. The implicit deny at the end of the ACL will then block all other traffic, achieving the desired policy.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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, then create an extended ACL with a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443, and apply it inbound on G0/1.
Why this is correct
This is correct because it removes the overly restrictive deny ip any any entry and replaces it with a permit statement that matches only HTTPS traffic from the specified source to destination. The implicit deny at the end of the ACL then blocks all other traffic, achieving the desired policy.
Related concept
Static NAT maps one inside address to one outside address.
✗
Add a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443 before the existing deny ip any any entry in the ACL.
Why it's wrong here
This is incorrect because ACLs process entries in order, and the deny ip any any entry will still match and block all traffic, including HTTPS, before the permit statement is evaluated.
✗
Remove the existing ACL and create a standard ACL with permit 192.0.2.0 0.0.0.255, then apply it inbound on G0/1.
Why it's wrong here
This is incorrect because standard ACLs can only match source IP addresses, not destination IP addresses or port numbers. They cannot filter based on TCP port 443, so they would permit all traffic from the source network, not just HTTPS.
✗
Remove the existing ACL and create an extended ACL with a permit statement for tcp any any eq 443, then apply it inbound on G0/1.
Why it's wrong here
This is incorrect because it permits HTTPS traffic from any source to any destination, which violates the requirement to restrict traffic only from 192.0.2.0/24 to 203.0.113.0/24.
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, then create an extended ACL with a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443, and apply it inbound on G0/1.Correct answer▾
Why this is correct
This is correct because it removes the overly restrictive deny ip any any entry and replaces it with a permit statement that matches only HTTPS traffic from the specified source to destination. The implicit deny at the end of the ACL then blocks all other traffic, achieving the desired policy.
✗Add a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443 before the existing deny ip any any entry in the ACL.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the order of entries matters; a deny any any at the end would block all traffic, but here it is placed before the permit, so the deny is evaluated first.
Why candidates choose this
Candidates might think that adding a permit statement before the deny will override it, but they overlook that the deny ip any any matches all traffic and will be hit first if placed before the permit.
✗Remove the existing ACL and create a standard ACL with permit 192.0.2.0 0.0.0.255, then apply it inbound on G0/1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that standard ACLs lack the capability to filter by protocol or port; extended ACLs are required for such granularity.
Why candidates choose this
Candidates might confuse standard and extended ACL capabilities, thinking a standard ACL can filter by port if applied correctly.
✗Remove the existing ACL and create an extended ACL with a permit statement for tcp any any eq 443, then apply it inbound on G0/1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the permit statement uses 'any' for source and destination, making it too permissive and not matching the specified networks.
Why candidates choose this
Candidates might focus only on the port number and forget to specify the source and destination networks, leading to an overly broad permit.
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: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
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.
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 the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
Network Services and Security — This question tests Network Services and Security — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Remove the existing ACL, then create an extended ACL with a permit statement for tcp 192.0.2.0 0.0.0.255 203.0.113.0 0.0.0.255 eq 443, and apply it inbound on G0/1. — The ACL BLOCK_IN currently has a single deny ip any any entry, which blocks all traffic inbound on G0/1. The correct solution is to first remove the existing ACL, then create a new extended ACL that permits TCP 443 from source network 192.0.2.0/24 to destination network 203.0.113.0/24, and apply it inbound on G0/1. The implicit deny at the end of the ACL will then block all other traffic, achieving the desired policy.
What should I do if I get this 200-301 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. An administrator needs to configure an ACL to block HTTP traffic from subnet 10.10.10.0/24 to the web server at 172.16.1.10 while permitting all other traffic. Which ACL entry should be placed first?
Why A: The ACL needs a narrow deny statement that matches only TCP port 80 from the specified source subnet to the specific server. In practical terms, the requirement is not to block all IP traffic or all access to the host. It is to stop normal HTTP while allowing everything else. That means the entry must be precise.
This is the kind of ACL question the CCNA exam likes because it forces you to distinguish protocol, destination, and service rather than relying on vague source-only logic.
Last reviewed: Jun 6, 2026
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