Question 1mediummulti select
Full question →mediummulti selectObjective-mapped
Which two statements about standard and extended IPv4 ACLs are correct?
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
An extended ACL cannot filter ICMP traffic.
Extended ACLs can match ICMP.
B
Best answer
A standard ACL matches only the source IPv4 address.
That is the key limitation of a standard ACL.
C
Best answer
An extended ACL can match protocol information and Layer 4 ports.
That is why extended ACLs are more specific.
D
Distractor review
A standard ACL is normally placed as close to the source as possible.
That placement guideline applies to extended ACLs.
E
Distractor review
Both ACL types require named ACL syntax to match traffic.
Numbered and named ACLs are both valid.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is assuming that standard ACLs can filter traffic based on protocol types or Layer 4 ports, which they cannot. This misconception leads to incorrect placement decisions, such as placing standard ACLs near the source, which risks blocking legitimate traffic from other sources. Another trap is believing extended ACLs cannot filter ICMP traffic, but extended ACLs do support ICMP filtering. Misunderstanding these facts can cause confusion in both exam scenarios and real-world network design, resulting in incorrect ACL configurations and ineffective traffic control.
Technical deep dive
How to think about this question
Access Control Lists (ACLs) are fundamental security tools in Cisco networking that control traffic flow by filtering packets based on defined criteria. Standard IPv4 ACLs filter traffic solely based on the source IPv4 address, making them simpler but less granular. Extended IPv4 ACLs provide more detailed filtering by matching source and destination IP addresses, Layer 4 protocols (such as TCP or UDP), and port numbers, enabling precise control over network traffic. The placement of ACLs in a network is guided by their filtering capabilities. Standard ACLs, due to their limited filtering scope, are generally placed closer to the destination to avoid blocking legitimate traffic from other sources. In contrast, extended ACLs, with their ability to filter specific protocols and ports, are placed closer to the source to prevent unwanted traffic from consuming network resources. Cisco IOS supports both numbered and named ACL configurations for both types, allowing flexible management. A common exam trap involves confusing the placement and filtering capabilities of standard and extended ACLs. Candidates might incorrectly assume standard ACLs filter based on protocol or ports or that extended ACLs cannot filter ICMP traffic. In practice, extended ACLs can filter ICMP, and their detailed filtering capabilities make them suitable for early traffic filtering near the source. Understanding these distinctions is crucial for correctly answering CCNA exam questions and for practical network security design.
KKey Concepts to Remember
- A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
- An extended IPv4 ACL can match source and destination IP addresses, Layer 4 protocols, and port numbers for granular filtering.
- Standard ACLs are typically placed closer to the destination to avoid unintentionally blocking legitimate traffic from other sources.
- Extended ACLs are usually placed closer to the source to filter unwanted traffic before it traverses the network.
- Both standard and extended ACLs can be configured using either numbered or named syntax on Cisco devices.
- Extended ACLs can filter traffic based on protocol types such as TCP, UDP, and ICMP, allowing more precise control.
- Standard ACLs cannot filter traffic based on Layer 4 port numbers or protocol types, limiting their filtering capability.
- Cisco IOS processes ACL entries in sequential order and stops at the first match, so order of statements is critical.
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?
A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
What is the correct answer to this question?
The correct answer is: A standard ACL matches only the source IPv4 address. — Standard ACLs match only the source IPv4 address, while extended ACLs can match protocol and source and destination details including ports. Because standard ACLs are less granular, they are usually placed closer to the destination. Extended ACLs are usually placed closer to the source.
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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