Passed Exam Today H12-811_V1.0

Detailed Explanation:Layer 2 switches operate at the data link layer, handling frames based on MAC addresses. They maintain a MAC address table to record mappings between MAC addresses and interfaces, allowing efficient frame forwarding within the local network. (Reference: HCIA-Datacom Training Material, Layer 2 Switching and MAC Address Learning)

In Huawei’s VRP, the default preference value for OSPF routes is generally 10, but this value can be adjusted based on configuration requirements. Therefore, it is not necessarily always set to 10, as network administrators may alter the preference to prioritize different routes. This flexibility allows customization based on the network ' s specific routing needs​.

A broadcast address, with all host bits set to 1, is used for broadcasting messages to all devices within a network segment. It cannot be assigned to a specific host, as its purpose is to reach every device in the subnet. Therefore, it is reserved for broadcast communication and cannot serve as an individual host address​.

The IPv4 header length is variable and is determined by the Header Length (IHL) field in the IPv4 header.

Minimum header size: 20 bytes (5 x 4B) → No options field.

Maximum header size: 60 bytes (15 x 4B) → Includes maximum options.

Option A (Incorrect - 64B): The maximum possible length of an IPv4 header is 60B, so 64B is not possible.

Option B (Correct - 20B): This is the standard IPv4 header size without options.

Option C (Correct - 60B): This is the maximum IPv4 header size with options.

Option D (Correct - 32B): This is a possible IPv4 header size with some options.

Thus, the correct answer is A (64B).