Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
ACL 15: access-list 15 deny 10.10.10.50 access-list 15 permit any Applied inbound on G0/0, the user LAN interface.
Exhibit: A standard ACL meant to block host 10.10.10.50 from reaching any remote network was applied inbound on the branch router's LAN interface, but users report that all local traffic from that host is now blocked. What is the better placement?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Leave it inbound on the LAN because standard ACLs belong near the source
Distractor.
B
Best answer
Move it outbound on the WAN-facing interface closer to the destination
Correct choice.
C
Distractor review
Convert it to a VTY access-class
Distractor.
D
Distractor review
Apply it inbound on all switch access ports
Distractor.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is believing that standard ACLs should always be applied inbound near the source to block unwanted traffic early. Since standard ACLs filter only by source IP, placing them inbound on a LAN interface can block all traffic from that host, including local communications within the LAN. This leads to unintended network outages and user complaints. The trap is confusing the ACL placement rule for extended ACLs, which are placed near the source, with the rule for standard ACLs, which should be placed near the destination to avoid over-blocking.
Technical deep dive
How to think about this question
Access Control Lists (ACLs) are fundamental tools in Cisco networking used to filter traffic based on defined criteria. Standard ACLs specifically filter traffic by matching only the source IP address, without regard to the destination or protocol. This simplicity means that any packet originating from a matched source IP will be filtered regardless of its intended destination. Because of this, standard ACLs are limited in granularity but are efficient for simple source-based filtering tasks. The placement of a standard ACL is crucial to its effectiveness and to avoid unintended network disruptions. The general rule for standard ACLs is to place them as close to the destination as possible. This ensures that only traffic destined for the remote network is filtered, while local traffic from the same source IP is allowed to pass freely. Placing a standard ACL near the source interface, such as inbound on a LAN interface, can block all traffic from that source IP, including local LAN traffic, which is often undesirable. A common exam trap is to assume that standard ACLs should always be placed near the source to block unwanted traffic early. However, because standard ACLs filter only by source IP, placing them near the source can inadvertently block legitimate local traffic. In practical Cisco network deployments, moving the standard ACL outbound on the WAN-facing interface aligns with best practices by filtering traffic as it leaves toward remote destinations, preserving local connectivity and minimizing unintended disruptions.
KKey Concepts to Remember
- A standard ACL filters traffic based solely on the source IP address and does not consider destination IP addresses in its matching criteria.
- Placing a standard ACL near the source interface can unintentionally block traffic to all destinations, including local networks, because it matches only source addresses.
- Best practice for standard ACL placement is close to the destination interface to limit the scope of traffic filtering and avoid blocking unintended traffic.
- Extended ACLs provide more granular control by filtering based on source and destination IP addresses, protocols, and ports, unlike standard ACLs.
- Inbound ACLs filter traffic as it enters an interface, while outbound ACLs filter traffic as it leaves an interface, affecting where the ACL impacts traffic flow.
- Applying a standard ACL inbound on a LAN interface can block all traffic from the specified source, including local LAN traffic, which may disrupt normal operations.
- Moving a standard ACL outbound on the WAN-facing interface targets traffic leaving the local network toward remote destinations, preserving local communication.
- Cisco routers process ACLs sequentially, and the first match determines the action, so ACL placement and order critically affect network traffic behavior.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
A standard ACL filters traffic based solely on the source IP address and does not consider destination IP addresses in its matching criteria.
What is the correct answer to this question?
The correct answer is: Move it outbound on the WAN-facing interface closer to the destination — A standard ACL matches only the source address. If it is placed near the source, it can block that host from reaching destinations you did not intend to affect. Standard ACLs are best placed close to the destination.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
Loading comments…
Sign in to join the discussion.