The correct answer is Standard ACL, because it is the only ACL type that filters traffic based solely on the source IP address, without considering destination, protocol, or port. Extended ACLs, by contrast, evaluate multiple criteria such as source and destination IP, protocol type, and port numbers, while Named ACLs allow administrators to assign a descriptive name instead of a number. On the CCNA 200-301 v2 exam, this distinction tests your ability to match ACL types to their core functions, often in drag-and-drop or multiple-choice questions where a common trap is confusing Standard ACLs with Extended ACLs due to their similar syntax. Remember that Standard ACLs are placed closest to the destination to avoid blocking unintended traffic, whereas Extended ACLs go closest to the source for precise control. A helpful memory tip: “Standard sees only the source; Extended examines everything in the packet.”
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 ACL filters traffic based solely on the source IP address, providing basic filtering capabilities.. 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.
Match each ACL-related term to its most accurate description.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Standard ACL
Standard ACLs use source IP only; extended ACLs use more criteria. Named ACLs use names; inbound/outbound specify direction. Implicit deny is the default deny-all at the end of any ACL.
Key principle: A standard ACL filters traffic based solely on the source IP address, providing basic filtering capabilities.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Standard ACL
Why this is correct
Standard ACLs filter traffic based solely on the source IP address, making them simpler but less granular than extended ACLs.
Related concept
A standard ACL filters traffic based solely on the source IP address, providing basic filtering capabilities.
✗
Extended ACL
Why it's wrong here
Extended ACLs filter based on source and destination IP, protocol, and port numbers, not just source IP.
✗
Named ACL
Why it's wrong here
Named ACLs use a name instead of a number for identification, but they still function as standard or extended ACLs.
✗
Implicit deny
Why it's wrong here
Implicit deny is a default rule that denies all traffic not explicitly permitted, not a type of ACL.
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.
✓Standard ACLCorrect answer▾
Why this is correct
Standard ACLs filter traffic based solely on the source IP address, making them simpler but less granular than extended ACLs.
✗Extended ACLWrong answer — click to see why▾
Why this is wrong here
Extended ACLs use multiple criteria, not only source IP.
Why candidates choose this
Candidates may confuse extended ACLs with standard ACLs, thinking both only use source IP.
✗Named ACLWrong answer — click to see why▾
Why this is wrong here
Named ACLs are not a separate type; they are just an alternative naming method.
Why candidates choose this
Candidates might think named ACLs have different filtering capabilities, but they are functionally identical to numbered ACLs.
✗Implicit denyWrong answer — click to see why▾
Why this is wrong here
Implicit deny is a behavior, not an ACL type.
Why candidates choose this
Candidates may mistakenly think implicit deny is a separate ACL type because it is always present at the end of any ACL.
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
Be careful not to confuse the types of ACLs: standard vs. extended. Also, remember that named ACLs are not a separate type; they are just an alternative naming method. Implicit deny is a behavior, not an ACL type.
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 ACLs filter traffic solely based on the source IP address, making them simpler but less granular. Extended ACLs provide more detailed filtering by considering source and destination IP addresses, protocols (such as TCP, UDP, ICMP), and port numbers, enabling precise control over network traffic. Wildcard masks are used in ACLs to specify which bits of an IP address should be matched exactly and which can vary, allowing flexible address matching.
When processing packets, ACLs evaluate entries sequentially from top to bottom. If a packet matches an ACL entry, the corresponding permit or deny action is applied immediately. If no entries match, an implicit deny at the end of every ACL silently blocks the packet. This implicit deny is not explicitly configured but is critical to understand because it can cause unexpected traffic drops if no permit statements match. Proper ACL design requires careful ordering of statements and understanding of wildcard masks to ensure intended traffic is allowed or blocked.
A common exam trap involves confusing standard and extended ACL capabilities or overlooking the implicit deny rule. Candidates may assume that an ACL permits all traffic not explicitly denied, but the implicit deny denies all unmatched traffic by default. Additionally, misunderstanding wildcard masks can lead to incorrect ACL entries that either over-permit or over-block traffic. In practical networks, ACLs must be carefully tested and applied to the correct interfaces and directions to enforce security policies effectively without disrupting legitimate traffic.
KKey Concepts to Remember
A standard ACL filters traffic based solely on the source IP address, providing basic filtering capabilities.
An extended ACL filters traffic based on source and destination IP addresses, protocols, and port numbers for granular control.
Wildcard masks in ACLs specify which bits of an IP address must match exactly and which bits can vary, enabling flexible matching.
ACLs process entries sequentially and apply the first matching permit or deny action to the packet.
Every ACL has an implicit deny at the end that blocks all traffic not explicitly permitted by preceding entries.
Proper ACL design requires ordering statements carefully to ensure intended traffic is permitted before the implicit deny.
Extended ACLs allow filtering by protocol type, such as TCP, UDP, or ICMP, which standard ACLs cannot do.
Applying ACLs on the correct interface and direction is essential to enforce security policies without unintended traffic disruption.
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 ACL filters traffic based solely on the source IP address, providing basic filtering capabilities.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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 ACL filters traffic based solely on the source IP address, providing basic filtering capabilities., 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 ACL filters traffic based solely on the source IP address, providing basic filtering capabilities..
What is the correct answer to this question?
The correct answer is: Standard ACL — Standard ACLs use source IP only; extended ACLs use more criteria. Named ACLs use names; inbound/outbound specify direction. Implicit deny is the default deny-all at the end of any ACL.
What should I do if I get this 200-301 question wrong?
Review a standard ACL filters traffic based solely on the source IP address, providing basic filtering capabilities., then practise related 200-301 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
A standard ACL filters traffic based solely on the source IP address, providing basic filtering capabilities.
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