CCNA Network Infrastructure and Connectivity Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  It maps learned MAC addresses to switch ports for local forwarding decisions.

  Why this is correct

  A switch builds its MAC address table by examining the source MAC addresses of incoming frames and associating them with the ingress port. This learned mapping is then used to make local forwarding decisions, allowing the switch to deliver frames directly to the port associated with the destination MAC address. This is the fundamental operation of Layer 2 switching.

• ✓

  It helps reduce unnecessary flooding when the destination MAC is known.

  Why this is correct

  When a frame arrives with a destination MAC that is present in the switch's MAC address table, the switch forwards it only out the specific port mapped to that MAC address. This targeted forwarding prevents unnecessary flooding to all other ports, thereby conserving bandwidth and reducing collisions. Flooding occurs only when the destination MAC is unknown or is a broadcast/multicast address.

• ✗

  It stores the best Layer 3 routes to remote networks.

  Why it's wrong here

  The best Layer 3 routes to remote networks are maintained in the routing table of a router or a multilayer switch's routing engine. A standard Layer 2 switch does not store or use IP routing information; it forwards frames based on MAC addresses within the local network. While some switches can perform routing, the role of a traditional switch does not include storing a route table to remote networks.

  When this WOULD be correct

  This option would be correct in a question that asks about the functions of a router's routing table, which does store the best Layer 3 routes to remote networks based on various routing protocols.

• ✗

  It contains the router’s OSPF authentication keys.

  Why it's wrong here

  OSPF authentication keys are security credentials used by routers to validate OSPF neighbor relationships and are stored in the router's configuration or keychain database. A switch's MAC address table contains only MAC-to-port mappings and contains no routing protocol authentication information. This option incorrectly associates switch forwarding functions with router security mechanisms, which is not part of a switch's role.

  When this WOULD be correct

  In a question focused on router configurations, if asked about the components of OSPF and their roles, option D could be correct if it specifically inquires about where OSPF authentication keys are stored within a router's configuration.

• ✗

  It assigns IP addresses to end hosts dynamically.

  Why it's wrong here

  Dynamic IP address assignment to end hosts is performed by a DHCP (Dynamic Host Configuration Protocol) server, which leases IP addresses to clients. A switch, functioning primarily at Layer 2, does not have the capability to allocate IP addresses; it focuses on forwarding frames based on MAC addresses. Even if a switch runs DHCP snooping, that is a security feature that does not itself assign addresses.

  When this WOULD be correct

  In a question asking about DHCP functionality, such as 'What mechanism is used to assign IP addresses dynamically to end hosts on a network?', option E would be correct as it directly relates to the role of DHCP servers in IP address allocation.

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.

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?”

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