The correct answer is to remove the two deny statements and add specific permit entries for VLAN 20, allowing all TCP ports except 80 and 443, followed by a final deny ip any any. This works because an extended ACL can filter traffic based on source and destination IP, protocol, and port numbers, allowing you to enforce granular per-VLAN policies. The original ACL incorrectly blocked HTTP/HTTPS globally, which prevented VLAN 20 from reaching the server on any TCP service except those ports. On the CCNA 200-301 v2 exam, this tests your ability to configure extended ACLs with port ranges and apply them directionally—a common trap is forgetting that deny statements affect all sources unless explicitly scoped. Remember that ACLs process top-down, so you must permit desired traffic before denying everything else. A helpful memory tip: "Permit the exceptions first, then block the rest"—for VLAN 20, permit all TCP except 80 and 443 by splitting the range into 1-79, 81-442, and 444-65535.
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 uses OSPF between R1 and R2. Configure an extended ACL on R1 so that hosts in VLAN 10 (192.168.10.0/24) can reach the web server at 203.0.113.100 only via HTTP/HTTPS, and hosts in VLAN 20 (192.168.20.0/24) can reach it via any TCP service except HTTP/HTTPS. All other traffic to the server must be denied. Apply the ACL outbound on the interface facing the server. Currently, the ACL is missing the permit for VLAN 20 traffic, causing connectivity loss.
R1# show running-config | section interface GigabitEthernet0/0
interface GigabitEthernet0/0
ip address 192.0.2.1 255.255.255.252
ip access-group BLOCK_HTTP in
duplex auto
speed auto
!
R1# show running-config | section access-list
ip access-list extended BLOCK_HTTP
deny tcp any 203.0.113.100 0.0.0.0 eq 80
deny tcp any 203.0.113.100 0.0.0.0 eq 443
permit ip 192.168.10.0 0.0.0.255 203.0.113.100 0.0.0.0
permit tcp 192.168.20.0 0.0.0.255 203.0.113.100 0.0.0.0 eq 22
permit tcp 192.168.20.0 0.0.0.255 203.0.113.100 0.0.0.0 eq 23
permit tcp 192.168.20.0 0.0.0.255 203.0.113.100 0.0.0.0 eq 443
permit tcp 192.168.20.0 0.0.0.255 203.0.113.100 0.0.0.0 eq 80
!
A
Remove the two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 79, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 81 442, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 444 65535, then deny ip any any
This correctly permits VLAN 20 to reach the server on all TCP ports except 80 and 443, while the existing permit statements for VLAN 10 allow HTTP/HTTPS. The explicit deny ip any any ensures all other traffic is denied. This matches the requirement that VLAN 20 can use any TCP service except HTTP/HTTPS.
B
Add a permit statement for VLAN 20 before the deny statements: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 65535
Why wrong: This is incorrect because it permits all TCP ports for VLAN 20, including HTTP/HTTPS, which violates the requirement that VLAN 20 cannot use HTTP/HTTPS. The requirement explicitly states VLAN 20 can reach the server via any TCP service except HTTP/HTTPS.
C
Remove the two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq www, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq 443
Why wrong: This is incorrect because it permits HTTP/HTTPS for VLAN 20, which is the opposite of what is required. The requirement states VLAN 20 should be denied HTTP/HTTPS but allowed other TCP services.
D
Add a deny statement for VLAN 20 HTTP/HTTPS before the existing permit statements: deny tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq www, deny tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq 443, then add a permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 65535
Why wrong: This is incorrect because the permit statement for VLAN 20 allows all TCP ports, including HTTP/HTTPS, which contradicts the deny statements. The deny statements are useless because the permit later allows everything. Also, the order is wrong; the permit should come after the denies, but the permit still allows HTTP/HTTPS.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove the two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 79, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 81 442, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 444 65535, then deny ip any any
The ACL BLOCK_HTTP is applied inbound on G0/0, which is the interface toward the server. The first two deny statements incorrectly block HTTP/HTTPS from any source, including VLAN 20 which should be allowed. The correct approach is to permit HTTP/HTTPS only for VLAN 10, and permit all other TCP services (except HTTP/HTTPS) for VLAN 20, then deny all other traffic. The solution removes the overly broad deny statements and adds specific permits for VLAN 20 to reach the server on any TCP port except 80 and 443, followed by an explicit deny ip any any to enforce the implicit deny.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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 two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 79, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 81 442, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 444 65535, then deny ip any any
Why this is correct
This correctly permits VLAN 20 to reach the server on all TCP ports except 80 and 443, while the existing permit statements for VLAN 10 allow HTTP/HTTPS. The explicit deny ip any any ensures all other traffic is denied. This matches the requirement that VLAN 20 can use any TCP service except HTTP/HTTPS.
Add a permit statement for VLAN 20 before the deny statements: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 65535
Why it's wrong here
This is incorrect because it permits all TCP ports for VLAN 20, including HTTP/HTTPS, which violates the requirement that VLAN 20 cannot use HTTP/HTTPS. The requirement explicitly states VLAN 20 can reach the server via any TCP service except HTTP/HTTPS.
✗
Remove the two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq www, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq 443
Why it's wrong here
This is incorrect because it permits HTTP/HTTPS for VLAN 20, which is the opposite of what is required. The requirement states VLAN 20 should be denied HTTP/HTTPS but allowed other TCP services.
✗
Add a deny statement for VLAN 20 HTTP/HTTPS before the existing permit statements: deny tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq www, deny tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq 443, then add a permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 65535
Why it's wrong here
This is incorrect because the permit statement for VLAN 20 allows all TCP ports, including HTTP/HTTPS, which contradicts the deny statements. The deny statements are useless because the permit later allows everything. Also, the order is wrong; the permit should come after the denies, but the permit still allows HTTP/HTTPS.
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 two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 79, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 81 442, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 444 65535, then deny ip any anyCorrect answer▾
Why this is correct
This correctly permits VLAN 20 to reach the server on all TCP ports except 80 and 443, while the existing permit statements for VLAN 10 allow HTTP/HTTPS. The explicit deny ip any any ensures all other traffic is denied. This matches the requirement that VLAN 20 can use any TCP service except HTTP/HTTPS.
✗Add a permit statement for VLAN 20 before the deny statements: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 65535Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the permit statement does not exclude ports 80 and 443. It allows all TCP ports, which is too permissive.
Why candidates choose this
Candidates might think that adding a permit for VLAN 20 before the deny statements will override them, but they overlook the need to exclude HTTP/HTTPS ports.
✗Remove the two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq www, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq 443Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the permit statements allow the very ports that should be denied for VLAN 20. This misinterprets the requirement.
Why candidates choose this
Candidates might confuse the requirements for VLAN 10 and VLAN 20, thinking both need HTTP/HTTPS access, or they might misread the question.
✗Add a deny statement for VLAN 20 HTTP/HTTPS before the existing permit statements: deny tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq www, deny tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 eq 443, then add a permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 65535Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the permit statement is too broad and overrides the deny statements. The correct approach is to permit only non-HTTP/HTTPS ports, not all ports.
Why candidates choose this
Candidates might think that adding deny statements for HTTP/HTTPS followed by a permit for all TCP will work, but they forget that the permit will allow HTTP/HTTPS anyway because ACLs are processed sequentially and the permit matches all TCP traffic.
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: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
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 OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
Network Services and Security — This question tests Network Services and Security — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: Remove the two deny statements and add: permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 1 79, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 81 442, permit tcp 192.168.20.0 0.0.0.255 host 203.0.113.100 range 444 65535, then deny ip any any — The ACL BLOCK_HTTP is applied inbound on G0/0, which is the interface toward the server. The first two deny statements incorrectly block HTTP/HTTPS from any source, including VLAN 20 which should be allowed. The correct approach is to permit HTTP/HTTPS only for VLAN 10, and permit all other TCP services (except HTTP/HTTPS) for VLAN 20, then deny all other traffic. The solution removes the overly broad deny statements and adds specific permits for VLAN 20 to reach the server on any TCP port except 80 and 443, followed by an explicit deny ip any any to enforce the implicit deny.
What should I do if I get this 200-301 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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