Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Why is an extended ACL usually placed close to the source of the traffic being filtered?
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
Because standard ACLs cannot be applied near the destination
That is not the reason for extended ACL placement guidance.
B
Best answer
To stop unwanted traffic earlier and conserve bandwidth
Correct. Filtering near the source is the classic design guidance for extended ACLs.
C
Distractor review
To make NAT translation easier on inside interfaces
That is not the primary ACL placement principle here.
D
Distractor review
Because extended ACLs only work inbound on access interfaces
Extended ACLs can be applied in multiple directions and places depending on design.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is confusing the placement rules for standard and extended ACLs. Candidates often assume that extended ACLs should be placed near the destination because they filter by source and destination, but this ignores the efficiency gained by filtering traffic as close to the source as possible. Another mistake is thinking extended ACLs only apply inbound, which is incorrect since Cisco devices allow flexible ACL direction. Misapplying these rules can cause unnecessary bandwidth consumption and network congestion, leading to incorrect answers on the exam.
Technical deep dive
How to think about this question
Extended Access Control Lists (ACLs) are a fundamental security feature in Cisco networking that filter traffic based on multiple criteria such as source IP, destination IP, protocol type, and port numbers. Unlike standard ACLs, which filter only by source IP address, extended ACLs provide granular control over traffic flows, enabling network administrators to permit or deny specific types of traffic. This capability is essential for enforcing security policies and optimizing network performance by controlling which packets are allowed to traverse the network. The placement of extended ACLs near the source of the traffic is a best practice because it prevents unwanted traffic from traveling across the network, thereby conserving bandwidth and reducing unnecessary load on intermediate devices. By filtering traffic as close as possible to its origin, the network avoids processing and forwarding packets that will ultimately be denied, which improves overall efficiency and security. This design principle contrasts with placing ACLs near the destination, which allows unwanted traffic to consume network resources before being dropped. A common exam trap is misunderstanding the difference between standard and extended ACL placement. Some candidates incorrectly believe that extended ACLs must be placed near the destination or that they only work inbound on interfaces. In reality, extended ACLs can be applied inbound or outbound and should be placed near the source to maximize efficiency. Misplacing extended ACLs can lead to suboptimal network performance and security gaps, which is why understanding the rationale behind ACL placement is critical for the CCNA exam and real-world network design.
KKey Concepts to Remember
- Extended ACLs filter traffic based on source IP, destination IP, protocol, and port numbers, enabling granular traffic control.
- Placing extended ACLs near the source of traffic prevents unwanted packets from consuming network bandwidth and resources downstream.
- Standard ACLs filter only by source IP and are typically placed near the destination to avoid blocking legitimate traffic prematurely.
- Extended ACLs can be applied inbound or outbound on interfaces, providing flexible deployment options based on network design.
- Filtering traffic early with extended ACLs improves network performance by reducing unnecessary processing on intermediate routers and switches.
- Misplacing extended ACLs near the destination can lead to inefficient bandwidth usage and increased network congestion.
- Understanding the difference between standard and extended ACL placement is critical to designing secure and efficient Cisco networks.
- Cisco devices process ACLs in sequential order, so placing extended ACLs near the source ensures early denial of unwanted traffic.
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.
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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?
Extended ACLs filter traffic based on source IP, destination IP, protocol, and port numbers, enabling granular traffic control.
What is the correct answer to this question?
The correct answer is: To stop unwanted traffic earlier and conserve bandwidth — Extended ACLs can filter by source, destination, and protocol. Placing them near the source drops unwanted traffic before it crosses more of the network.
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.
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