Quick Answer
The answer is applying ACLs to permit or deny traffic, along with forwarding packets based on destination MAC addresses for Layer 2 switching. These are correct because the data plane, also known as the forwarding plane, handles the actual per-packet processing in a network device, executing lookups in the forwarding table and applying hardware or software logic to decide where to send each frame or packet. ACL evaluation occurs during this forwarding process, making it a core data plane function rather than a control or management plane task. On the Cisco DevNet Associate 200-901 exam, this distinction tests your understanding of the separation between planes: the control plane builds the forwarding table, while the data plane uses it to move traffic. A common trap is confusing ACL application with the control plane, but remember that ACLs are enforced on every packet in the data path. A useful memory tip is “Data does the deed”—the data plane directly acts on traffic, applying rules and forwarding it without making routing decisions.
This 200-901 practice question tests your understanding of network fundamentals. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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 functions are performed by the data plane in a network device? (Choose two.)
Building the routing table using OSPF
Why wrong: Control plane function.
Forwarding packets based on destination MAC address
Data plane performs forwarding.
Applying ACLs to permit or deny traffic
Data plane performs packet filtering.
Maintaining ARP cache entries
Why wrong: Control plane function.
Establishing OSPF neighbor adjacencies
Why wrong: Control plane function.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Forwarding packets based on destination MAC address
The data plane is responsible for forwarding packets based on information in the forwarding table, such as destination MAC address for Layer 2 switching. Applying ACLs is also a data plane function because ACL rules are evaluated in hardware or software during packet forwarding to permit or deny traffic.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Building the routing table using OSPF
Why it's wrong here
Control plane function.
Forwarding packets based on destination MAC address
Why this is correct
Data plane performs forwarding.
Related concept
Read the scenario before looking for a memorised answer.
Applying ACLs to permit or deny traffic
Why this is correct
Data plane performs packet filtering.
Related concept
Read the scenario before looking for a memorised answer.
Maintaining ARP cache entries
Why it's wrong here
Control plane function.
Establishing OSPF neighbor adjacencies
Why it's wrong here
Control plane function.
Common exam traps
Cisco often tests the distinction between control plane and data plane by listing functions that sound like forwarding (e.g., maintaining ARP cache) but are actually control plane operations, leading candidates to confuse maintenance with usage.
Detailed technical explanation
In Cisco IOS, the data plane is often implemented in hardware using ASICs (e.g., Cisco Express Forwarding) to achieve line-rate forwarding. ACLs applied to interfaces are compiled into TCAM entries that are matched during packet forwarding, making ACL processing a data plane operation. The control plane, by contrast, handles routing protocols like OSPF (RFC 2328) and ARP (RFC 826) via the CPU.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
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FAQ
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: Forwarding packets based on destination MAC address — The data plane is responsible for forwarding packets based on information in the forwarding table, such as destination MAC address for Layer 2 switching. Applying ACLs is also a data plane function because ACL rules are evaluated in hardware or software during packet forwarding to permit or deny traffic.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This 200-901 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-901 exam.
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