Question 1mediummulti select
Full question →mediummulti selectObjective-mapped
Which two statements accurately describe the role of a switch MAC address table?
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
It maps learned MAC addresses to switch ports for local forwarding decisions.
This is correct because that is the core purpose of the MAC address table.
B
Best answer
It helps reduce unnecessary flooding when the destination MAC is known.
This is correct because once a destination MAC is known, the switch can forward more selectively.
C
Distractor review
It stores the best Layer 3 routes to remote networks.
This is wrong because routing tables, not MAC tables, handle Layer 3 path decisions.
D
Distractor review
It contains the router’s OSPF authentication keys.
This is wrong because MAC tables do not store OSPF security information.
E
Distractor review
It assigns IP addresses to end hosts dynamically.
This is wrong because DHCP assigns IP addresses.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking the MAC address table for a routing or security database. Some candidates incorrectly believe the MAC table stores Layer 3 routing information, OSPF authentication keys, or DHCP IP assignments. This confusion arises because switches and routers often coexist, but their functions differ. The MAC address table only tracks MAC addresses and their associated switch ports to make local forwarding decisions. Misunderstanding this can lead to selecting incorrect answers related to routing protocols or IP address management, which are outside the MAC table’s scope.
Technical deep dive
How to think about this question
A switch MAC address table is a fundamental component in Layer 2 switching that maps MAC addresses to specific switch ports. When a switch receives a frame, it examines the source MAC address and records which port the frame arrived on. This learning process builds the MAC address table dynamically, enabling the switch to forward frames intelligently. Instead of broadcasting frames to all ports, the switch uses the MAC address table to send frames only to the port associated with the destination MAC address, optimizing network efficiency. The MAC address table supports local forwarding decisions by associating each learned MAC address with a single switch port. When a frame arrives destined for a known MAC address, the switch consults the table and forwards the frame only to the corresponding port, reducing unnecessary flooding. If the destination MAC address is unknown, the switch floods the frame out all ports except the source port, ensuring delivery while learning new MAC addresses. This behavior contrasts with routing tables, which operate at Layer 3 and determine paths to remote networks. A common exam trap is confusing the MAC address table with routing or security functions. The MAC table does not store Layer 3 routes, OSPF authentication keys, or DHCP assignments. Instead, it strictly manages MAC-to-port mappings for local switching. Practically, this means that switches efficiently forward Ethernet frames within the same broadcast domain, while routers handle inter-network traffic. Understanding this distinction helps avoid misinterpreting the MAC table’s role and prevents errors on the CCNA exam.
KKey Concepts to Remember
- A switch learns MAC addresses dynamically by recording the source MAC and the ingress port of received frames into its MAC address table.
- The MAC address table enables the switch to forward frames only to the port associated with the destination MAC address, reducing unnecessary network flooding.
- If the destination MAC address is unknown, the switch floods the frame out all ports except the source port to ensure delivery and learn new MAC addresses.
- The MAC address table operates at Layer 2 and is distinct from routing tables, which handle Layer 3 path selection to remote networks.
- Switches do not use the MAC address table to store OSPF authentication keys or any Layer 3 routing protocol security information.
- Dynamic Host Configuration Protocol (DHCP) assigns IP addresses and is unrelated to the MAC address table’s function of MAC-to-port mapping.
- Efficient MAC address table management improves network performance by minimizing broadcast traffic and localizing frame forwarding.
- The MAC address table is essential for VLAN-aware switches to maintain separate MAC address mappings per VLAN, ensuring proper traffic segregation.
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 switch learns MAC addresses dynamically by recording the source MAC and the ingress port of received frames into its MAC address table.
What is the correct answer to this question?
The correct answer is: It maps learned MAC addresses to switch ports for local forwarding decisions. — A switch MAC address table helps the switch make local forwarding decisions efficiently. In plain language, the switch learns which MAC addresses appear on which ports and then uses that information to send frames only where they need to go instead of flooding every frame everywhere. The MAC table is not the same thing as a routing table, and it is not used for OSPF neighbor storage or DHCP lease records.
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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