CCNA Network Services and Security Practice Question
This 200-301 practice question tests your understanding of network services and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: a standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.. 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.
Which two statements about standard and extended IPv4 ACLs are correct?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
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.
Key principle: A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
A standard ACL matches only the source IPv4 address.
A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
✓
An extended ACL can match protocol information and Layer 4 ports.
Why this is correct
That is why extended ACLs are more specific.
Related concept
A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
✗
A standard ACL is normally placed as close to the source as possible.
Why it's wrong here
That placement guideline applies to extended ACLs.
When this WOULD be correct
In a question that asks about the placement of ACLs specifically for optimizing bandwidth usage or reducing load on upstream devices, option C could be correct if it stated that a standard ACL is placed close to the source to filter traffic before it enters the network.
In a different exam question asking specifically about the capabilities of standard ACLs versus extended ACLs in filtering traffic types, if the question stated that extended ACLs cannot filter ICMP, then option D would be correct, as it would align with the constraints of that specific scenario.
✗
Both ACL types require named ACL syntax to match traffic.
Why it's wrong here
Numbered and named ACLs are both valid.
When this WOULD be correct
In a scenario where the exam question specifies that only named ACLs are allowed for configuration, and asks which types of ACLs can be used, option E would be correct if both standard and extended ACLs were defined to require named syntax exclusively.
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.
✓A standard ACL matches only the source IPv4 address.Correct answer▾
Why this is correct
That is the key limitation of a standard ACL.
✗A standard ACL is normally placed as close to the source as possible.Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because a standard ACL is typically placed as close to the destination as possible to minimize unnecessary traffic on the network, not at the source. The placement of ACLs is critical for effective traffic filtering.
★ When this WOULD be the correct answer
In a question that asks about the placement of ACLs specifically for optimizing bandwidth usage or reducing load on upstream devices, option C could be correct if it stated that a standard ACL is placed close to the source to filter traffic before it enters the network.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of ACL placement strategies, confusing the general practice of placing access lists with the specific type of ACL being discussed.
✗An extended ACL cannot filter ICMP traffic.Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because extended ACLs can indeed filter ICMP traffic, as they are designed to match various protocols, including ICMP, based on both source and destination IP addresses and Layer 4 ports.
★ When this WOULD be the correct answer
In a different exam question asking specifically about the capabilities of standard ACLs versus extended ACLs in filtering traffic types, if the question stated that extended ACLs cannot filter ICMP, then option D would be correct, as it would align with the constraints of that specific scenario.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of the capabilities of extended ACLs, often confusing them with standard ACLs, which only filter based on source IP addresses and do not consider protocol types.
✗Both ACL types require named ACL syntax to match traffic.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because standard and extended ACLs can be defined using both numbered and named syntax; named ACLs are not a requirement for either type. Therefore, stating that both require named ACL syntax is misleading.
★ When this WOULD be the correct answer
In a scenario where the exam question specifies that only named ACLs are allowed for configuration, and asks which types of ACLs can be used, option E would be correct if both standard and extended ACLs were defined to require named syntax exclusively.
Why candidates choose this
Candidates may find this option tempting because they might confuse the use of named ACLs with the general configuration of ACLs, leading them to believe that named syntax is a necessity for both types.
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: 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.
Detailed technical explanation
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.
Key takeaway
A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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 a standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic., then practise related 200-301 questions on the same topic to reinforce the concept.
Network Services and Security — This question tests Network Services and Security — 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?
Review a standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
A standard IPv4 ACL matches only the source IPv4 address in the packet header to permit or deny traffic.
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