Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
As a general rule, where should an extended ACL be placed?
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
Best answer
As close to the source as practical
Correct. This is the common placement guideline.
B
Distractor review
As close to the destination as possible in all cases
That guidance is more often associated with standard ACLs.
C
Distractor review
Only on the default gateway
Extended ACLs are not limited to default gateways.
D
Distractor review
Only on WAN interfaces
They are not limited to WAN interfaces.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting option B, which suggests placing extended ACLs as close to the destination as possible. This is a common misconception because it confuses extended ACL placement with standard ACL placement. Standard ACLs filter only on source IP addresses and are best placed near the destination to avoid blocking legitimate traffic prematurely. Extended ACLs, however, filter on both source and destination IP addresses and protocols, allowing them to be safely placed near the source to block unwanted traffic early. Misunderstanding this difference can lead to inefficient traffic filtering and potential network performance issues.
Technical deep dive
How to think about this question
Access Control Lists (ACLs) are fundamental security tools in Cisco networking used to filter traffic based on defined criteria such as source/destination IP addresses, protocols, and ports. Extended ACLs provide granular control by filtering traffic based on multiple parameters, including source and destination IP addresses and Layer 4 protocols, enabling precise traffic filtering beyond what standard ACLs offer. The general rule for placing extended ACLs is to position them as close to the source of the traffic as practical. This placement ensures that unwanted traffic is blocked early in the network path, conserving bandwidth and reducing unnecessary processing on intermediate devices. By filtering traffic near the source, the network avoids carrying unwanted packets across multiple links, which optimizes resource utilization and enhances overall network performance. A common exam trap is to confuse the placement of extended ACLs with that of standard ACLs. Standard ACLs are typically placed near the destination because they filter only on source IP addresses, which can inadvertently block legitimate traffic if placed near the source. Extended ACLs, however, filter on both source and destination, allowing safe placement near the source. Understanding this distinction is critical for both exam success and practical network security design.
KKey Concepts to Remember
- Extended ACLs filter traffic based on source and destination IP addresses as well as Layer 4 protocol information, enabling precise traffic control.
- Placing extended ACLs near the source prevents unwanted traffic from traversing the network, conserving bandwidth and device resources.
- Standard ACLs filter only on source IP addresses and are typically placed near the destination to avoid blocking legitimate traffic prematurely.
- Extended ACL placement near the source allows early traffic filtering without impacting legitimate flows, improving network efficiency.
- Incorrectly placing extended ACLs near the destination can allow unwanted traffic to consume network resources unnecessarily.
- Cisco devices process ACLs in sequential order, so the placement and order of ACL entries directly affect traffic filtering behavior.
- Understanding the difference between standard and extended ACL placement is critical for effective network security and CCNA exam success.
- Extended ACLs are not limited to default gateways or WAN interfaces; they can be applied on any interface near the traffic source.
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 and destination IP addresses as well as Layer 4 protocol information, enabling precise traffic control.
What is the correct answer to this question?
The correct answer is: As close to the source as practical — Extended ACLs are commonly placed near the source to stop unwanted traffic earlier and conserve bandwidth and device resources.
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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