Exam H12-811_V2.0 Topic 2 Question 109 Discussion

This statement is true . ARP is a Layer 2 broadcast-based protocol used to resolve an IPv4 address into a MAC address within the same broadcast domain. If two PCs are connected to the same switch but cannot learn each other's ARP entries, one likely reason is an incorrect VLAN configuration .
For example, if PC1 and PC2 are placed in different VLANs, or if one interface is configured with the wrong access VLAN, ARP broadcast frames from one PC will not reach the other PC because VLANs separate Layer 2 broadcast domains. As a result, the ARP request will not be received by the peer, and the MAC address cannot be resolved. Other causes may also exist, such as incorrect IP addressing, port isolation, or security policies, but VLAN misconfiguration is a very common and valid cause in campus switching scenarios. HCIA-Datacom teaches that ARP communication depends on correct Layer 2 domain membership, and VLAN planning or interface configuration errors often directly affect host-to-host communication even when both hosts are physically connected to the same switch.